import java.util.*;
import java.lang.*;
import java.io.*;

// The main method must be in a class named "Main".
class Main {
    public static void main(String[] args) {
        System.out.println("Hello world!");
    
        // Problem1_2
        System.out.print("ABC\nDEF\nGHI\n");

        // Problem1_3
        System.out.println(1 + " + " + 1 + " = " + (1+1));
        System.out.println(2 + " + " + 3 + " = " + (2+3));

        // Problem1_4
        System.out.println(1 + " + " + 2 + " + " + 3 " = " + (1+2+30))
    }
}