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(){

int x,y,t,k,i;

scanf("%d %d\n",&x,&y);

if(y>x){
 t = y;
 y = x;
 x = t;
}
k = 0;

for(i=1;i<=y;i++){
 if((y%i==0) && (x%i==0)){
  k = i;
  }
}

printf("%d\n",k);

return 0;
}