diff --git a/src/ast_parser/BinaryOperatorExpr.java b/src/ast_parser/BinaryOperatorExpr.java
new file mode 100644
index 0000000..ce75ae8
--- /dev/null
+++ b/src/ast_parser/BinaryOperatorExpr.java
@@ -0,0 +1,24 @@
+package ast_parser;
+
+class BinaryOperatorExpr extends Expr {
+    Expr left;
+    Expr right;
+    char operator;
+
+    BinaryOperatorExpr(Expr left, Expr right, char operator) {
+        this.left = left;
+        this.right = right;
+        this.operator = operator;
+    }
+
+    @Override
+    double evaluate() {
+        return switch (operator) {
+            case '+' -> left.evaluate() + right.evaluate();
+            case '-' -> left.evaluate() - right.evaluate();
+            case '*' -> left.evaluate() * right.evaluate();
+            case '/' -> left.evaluate() / right.evaluate();
+            default -> throw new RuntimeException("Unsupported operator: " + operator);
+        };
+    }
+}
diff --git a/src/ast_parser/Expr.java b/src/ast_parser/Expr.java
new file mode 100644
index 0000000..d69a6ba
--- /dev/null
+++ b/src/ast_parser/Expr.java
@@ -0,0 +1,5 @@
+package ast_parser;
+
+abstract class Expr {
+    abstract double evaluate();
+}
diff --git a/src/ast_parser/FunctionExpr.java b/src/ast_parser/FunctionExpr.java
new file mode 100644
index 0000000..f221a34
--- /dev/null
+++ b/src/ast_parser/FunctionExpr.java
@@ -0,0 +1,50 @@
+package ast_parser;
+
+import java.util.List;
+
+class FunctionExpr extends Expr {
+    String function;
+    List<Expr> arguments;
+
+    FunctionExpr(String function, List<Expr> arguments) {
+        this.function = function;
+        this.arguments = arguments;
+    }
+
+    @Override
+    double evaluate() {
+        return switch (function) {
+            case "sqrt" -> {
+                if (arguments.size() != 1) {
+                    throw new RuntimeException("sqrt expects exactly one argument");
+                }
+                yield Math.sqrt(arguments.get(0).evaluate());
+            }
+            case "logtwo" -> {
+                if (arguments.size() != 1) {
+                    throw new RuntimeException("log2 expects exactly one argument");
+                }
+                yield Math.log(arguments.get(0).evaluate()) / Math.log(2);
+            }
+            case "logten" -> {
+                if (arguments.size() != 1) {
+                    throw new RuntimeException("log10 expects exactly one argument");
+                }
+                yield Math.log10(arguments.get(0).evaluate());
+            }
+            case "loge" -> {
+                if (arguments.size() != 1) {
+                    throw new RuntimeException("loge expects exactly one argument");
+                }
+                yield Math.log(arguments.get(0).evaluate());
+            }
+            case "powtwo" -> {
+                if (arguments.size() != 1) {
+                    throw new RuntimeException("pow2 expects exactly one argument");
+                }
+                yield Math.pow(2, arguments.get(0).evaluate());
+            }
+            default -> throw new RuntimeException("Unsupported function or wrong number of arguments: " + function);
+        };
+    }
+}
diff --git a/src/ast_parser/Lexer.java b/src/ast_parser/Lexer.java
new file mode 100644
index 0000000..84519ab
--- /dev/null
+++ b/src/ast_parser/Lexer.java
@@ -0,0 +1,51 @@
+package ast_parser;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Lexer {
+    public static List<Token> tokenize(String input) {
+        List<Token> tokens = new ArrayList<>();
+        input = input.replaceAll("\\s", "");
+        int i = 0;
+        while (i < input.length()) {
+            char ch = input.charAt(i);
+            if (Character.isDigit(ch)) {
+                StringBuilder sb = new StringBuilder();
+                while (i < input.length() && (Character.isDigit(input.charAt(i)) || input.charAt(i) == '.')) {
+                    sb.append(input.charAt(i));
+                    i++;
+                }
+                tokens.add(new Token(TokenType.NUMBER, sb.toString()));
+            } else if (Character.isLetter(ch)) {
+                StringBuilder sb = new StringBuilder();
+                while (i < input.length() && Character.isLetter(input.charAt(i))) {
+                    sb.append(input.charAt(i));
+                    i++;
+                }
+                tokens.add(new Token(TokenType.FUNCTION, sb.toString()));
+            } else {
+                switch (ch) {
+                    case '(':
+                        tokens.add(new Token(TokenType.LPAREN, "("));
+                        i++;
+                        break;
+                    case ')':
+                        tokens.add(new Token(TokenType.RPAREN, ")"));
+                        i++;
+                        break;
+                    case ',':
+                        tokens.add(new Token(TokenType.COMMA, ","));
+                        i++;
+                        break;
+                    default:
+                        tokens.add(new Token(TokenType.OPERATOR, String.valueOf(ch)));
+                        i++;
+                        break;
+                }
+            }
+        }
+        tokens.add(new Token(TokenType.EOF, ""));
+        return tokens;
+    }
+}
diff --git a/src/ast_parser/MainParser.java b/src/ast_parser/MainParser.java
new file mode 100644
index 0000000..2ea4f28
--- /dev/null
+++ b/src/ast_parser/MainParser.java
@@ -0,0 +1,17 @@
+package ast_parser;
+
+import java.util.List;
+
+public class MainParser {
+    public static void main(String[] args) {
+        String input = "(3 + 5) * sqrt(16) + powtwo(5)";
+        List<Token> tokens = Lexer.tokenize(input);
+        System.out.println("Tokens:");
+        tokens.forEach(System.out::println);
+
+        Parser parser = new Parser(tokens);
+        Expr expression = parser.parse();
+        double result = expression.evaluate();
+        System.out.println("Result: " + result);
+    }
+}
diff --git a/src/ast_parser/NumberExpr.java b/src/ast_parser/NumberExpr.java
new file mode 100644
index 0000000..28bb7fa
--- /dev/null
+++ b/src/ast_parser/NumberExpr.java
@@ -0,0 +1,14 @@
+package ast_parser;
+
+class NumberExpr extends Expr {
+    double value;
+
+    NumberExpr(double value) {
+        this.value = value;
+    }
+
+    @Override
+    double evaluate() {
+        return value;
+    }
+}
diff --git a/src/ast_parser/Parser.java b/src/ast_parser/Parser.java
new file mode 100644
index 0000000..6831f5f
--- /dev/null
+++ b/src/ast_parser/Parser.java
@@ -0,0 +1,78 @@
+package ast_parser;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class Parser {
+    private final List<Token> tokens;
+    private int current = 0;
+
+    public Parser(List<Token> tokens) {
+        this.tokens = tokens;
+    }
+
+    public Expr parse() {
+        return expression();
+    }
+
+    private Expr expression() {
+        Expr expr = term();
+        while (match(TokenType.OPERATOR)) {
+            char operator = tokens.get(current - 1).value.charAt(0);
+            Expr right = term();
+            expr = new BinaryOperatorExpr(expr, right, operator);
+        }
+        return expr;
+    }
+
+    private Expr term() {
+        if (match(TokenType.NUMBER)) {
+            return new NumberExpr(Double.parseDouble(previous().value));
+        } else if (match(TokenType.LPAREN)) {
+            Expr expr = expression();
+            consume(TokenType.RPAREN, "Expect ')' after expression.");
+            return expr;
+        } else if (match(TokenType.FUNCTION)) {
+            String functionName = previous().value;
+            consume(TokenType.LPAREN, "Expect '(' after function name.");
+            List<Expr> args = new ArrayList<>();
+            if (!check(TokenType.RPAREN)) {
+                do {
+                    args.add(expression());
+                } while (match(TokenType.COMMA));
+            }
+            consume(TokenType.RPAREN, "Expect ')' after arguments.");
+            return new FunctionExpr(functionName, args);
+        }
+        throw new RuntimeException("Unexpected token.");
+    }
+
+    private boolean match(TokenType type) {
+        if (check(type)) {
+            current++;
+            return true;
+        }
+        return false;
+    }
+
+    private boolean check(TokenType type) {
+        if (isAtEnd()) return false;
+        return tokens.get(current).type == type;
+    }
+
+    private Token previous() {
+        return tokens.get(current - 1);
+    }
+
+    private void consume(TokenType type, String message) {
+        if (check(type)) {
+            current++;
+            return;
+        }
+        throw new RuntimeException(message);
+    }
+
+    private boolean isAtEnd() {
+        return current >= tokens.size() || tokens.get(current).type == TokenType.EOF;
+    }
+}
diff --git a/src/ast_parser/Token.java b/src/ast_parser/Token.java
new file mode 100644
index 0000000..89faaad
--- /dev/null
+++ b/src/ast_parser/Token.java
@@ -0,0 +1,16 @@
+package ast_parser;
+
+public class Token {
+    public TokenType type;
+    public String value;
+
+    public Token(TokenType type, String value) {
+        this.type = type;
+        this.value = value;
+    }
+
+    @Override
+    public String toString() {
+        return type + " : " + value;
+    }
+}
diff --git a/src/ast_parser/TokenType.java b/src/ast_parser/TokenType.java
new file mode 100644
index 0000000..fdb715b
--- /dev/null
+++ b/src/ast_parser/TokenType.java
@@ -0,0 +1,11 @@
+package ast_parser;
+
+public enum TokenType {
+    NUMBER,
+    OPERATOR,
+    LPAREN,
+    RPAREN,
+    FUNCTION,
+    COMMA,
+    EOF
+}
diff --git a/src/reports/lab_five.pdf b/src/reports/lab_five.pdf
new file mode 100644
index 0000000..c354dec
Binary files /dev/null and b/src/reports/lab_five.pdf differ