辗转相除法和__gcd库

#include<bits/stdc++.h>
using namespace std;

int gcd(int a,int b)
{
    if(b==0)
        return a;
    else
        gcd(b,a%b);
}

int main()
{
    int x,y;
    while(cin>>x>>y)
    {
        cout<<__gcd(x,y)<<endl;
        cout<<gcd(x,y)<<endl;
    }
}