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 C (judge verdict: Time Limit Exceeded)

#include<stdio.h>
int main(void){
   int a,b,x,y,r;
   scanf("%d %d",&a,&b);
   if(a<b){
      x=b;y=a;}
   else if(a>b){
      x=a;y=b;}
      
   while(y>0)
      r=x%y;
      x=y;
      y=r;
   printf("%d",x);
return 0;
   
}