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, c, d, i, x, y;

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

    if (x > y)
        a = y, b = x;
    else
        a = x, b = y;

    c = a / 2;

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

    if (b % a == 0)
        d = a;

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

    return 0;

}