Problem:
Greatest Common Divisor

Write a program which finds the greatest common divisor of two natural numbers a and b

Input

a and b are given in a line sparated by a single space.

Output

Output the greatest common divisor of a and b.

Constrants

1 ≤ a, b ≤ 109

Hint

You can use the following observation:

For integers x and y, if x ≥ y, then gcd(x, y) = gcd(y, x%y)

Sample Input 1

54 20

Sample Output 1

2

Sample Input 2

147 105

Sample Output 2

21

Solution in JavaScript (judge verdict: Accepted)

var input = require('fs').readFileSync('/dev/stdin', 'utf8');
var Arr=input.split("\n");
var A=Arr[0].split(" ").map(Number);

gcd(A[0],A[1]);

function gcd(x,y){
    
    if(x>y){
        if((x % y) === 0){
            console.log(y);
        }else{
            gcd(y,x%y);
        }
    }else{
        if((y % x) === 0){
            console.log(x);
        }else{
            gcd(x,y%x);
        }
    }

}