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, GCD;
    scanf("%d",&a);
    scanf("%d",&b);
    if(a>=1&&b>=1&&a<=1000000000&&b<=1000000000)
    {
        for(i = 1; i <= a && i <= b; i++)
    {
        if(a % i == 0 && b % i == 0)
            GCD = i;
    }
    printf("%d\n", GCD);
    }
    return 0;
}