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 a,b,i,num,Max;

  scanf("%d%d",&a,&b);
  
  if(a > b) num = b;
  else num = a;

for(i=num; i>=1; i--){
    if(a%i==0 && b%i==0){
        Max=i;
        break;
    }
}
  printf("%d\n",Max);
}