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: Accepted)

#include<stdio.h>
int main(){
  int x,y,z,p,q;
  int a,i;
  scanf("%d %d",&x,&y);

  if(x>=y)
    {
      p=x;
      q=y;
    }
  else if(x<=y){
    q=x;
    p=y;
  }
  z=p%q;
  a=1;
  if(z==0){
    printf("%d\n",x);
  }
  else if(z!=0){
    for(i=1;i<=z;i++){
    if(z%i==0 && q%i==0){
      if(i>=a){
        a=i;
    }
    }
    }
  printf("%d\n",a);
  }
  return 0;

}