//  Greatest Common Divisor of two integeres according to Euclid's algorithm:
//  If B=0 then Return A else Return Euclid(B, A mod B)


import java.io.*;

class Euclid-gcd {

  public static void main (String[] args) throws IOException {

    int a, b, t;

    BufferedReader stdin;
    stdin = new BufferedReader (new InputStreamReader (System.in));

    System.out.print ("Enter first integer: ");
    a = Integer.parseInt (stdin.readLine());
    System.out.print ("Enter second integer: ");
    b = Integer.parseInt (stdin.readLine());

    while (b > 0) { 
       t = a % b; 
       a = b; 
       b = t; 
    } 

    System.out.print ("Their GCD is: " + a);
     
  }
}