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 a,b,max,d=1,c,e;
  scanf("%d %d",&a,&b);
  if(a<b){
    e=a;
    a=b;
    b=e;
  }
  c=a%b;
  if(c==0){
    max=a;
  }else if(b<c){
    for(d=1;d<=b;d++){
      if(b%d==0 && c%d==0){
	max=d;
      }
    }
  }else{
    for(d=1;d<=c;d++){
      if(b%d==0 && c%d==0){
	max=d;
      }
    }
  }
  printf("%d\n",max);
}