using System;

public class Program

{

    public static void Main()

    {

        //GCD

        Console.WriteLine(GCD(16,4));

        //LCM

        Console.WriteLine(LCM(16,4));

        // Multiply without *

        Console.WriteLine(multiply(5,4));

        //Divide without /

        Console.WriteLine(divide(1000,2));

    }

    public static int multiply(int a, int b){

        if(b == 0){

            return 0;   

        }

        if(b > 0){

            return a + multiply(a, b - 1);  

        }

        if(b < 0){

            return -multiply(a, -b);    

        }

        return a;

    }

    public static int GCD(int x, int y){

        if(y == 0){

            return x;   

        }

        return GCD(y, x%y);

    }

    public static int LCM(int x, int y){

        return (x*y) / GCD (x,y);   

    }

    public static int divide(int dividend, int divisor){

        int quotient = 0;

        int sign = 1;

        if(dividend < 0) {

            dividend *= -1;

            sign = -1;

        }

        if(divisor < 0){ 

            divisor *= -1;

            sign = -1;

        }

        while(dividend >= divisor){

            dividend -= divisor;

            quotient++;

        }

        return quotient * sign;

    }

}