public class MathOperations {

    // Method to add two integers
    public int add(int a, int b) {
        return a + b;
    }

    // Method to add three integers
    public int add(int a, int b, int c) {
        return a + b + c;
    }

    // Method to add two doubles
    public double add(double a, double b) {
        return a + b;
    }

    // Method to concatenate two strings
    public String add(String a, String b) {
        return a + b;
    }

    public static void main(String[] args) {
        MathOperations math = new MathOperations();

        // Test the overloaded methods
        System.out.println("Addition of two integers: " + math.add(10, 20));
        System.out.println("Addition of three integers: " + math.add(10, 20, 30));
        System.out.println("Addition of two doubles: " + math.add(10.5, 20.5));
        System.out.println("Concatenation of two strings: " + math.add("Hello", " World"));
    }
}