GCD模板

#include<cstdio>
using namespace std;

int gcd(int a,int b)
{
    int r;
    while(b>0)
    {
        r=a%b;
        a=b;
        b=r;
    }
    return a;
}

int main()
{
    int a,b;
    while(scanf("%d%d",&a,&b)==2)
    {
        printf("%d\n",gcd(a,b));
    }
    return 0;
}