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>
#include <stdlib.h>

int gcd(int a, int b){
	int n = b/2;
	int result;
	if(a%b==0) return b;
	else{
		for(int i=1; i<=n; i++){
			int flag = (a%i==0) & (b%i==0);
			if(flag == 1) result = i; 	
		}
		return result;
	}
}

int main(int argc, char const *argv[]){
	// Input 2 natural numbers 
	int a,b;
	scanf("%d %d", &a, &b);
	if(a>=b) printf("%d\n", gcd(a,b));
	else	 printf("%d\n", gcd(b,a));
	return 0;
}