gcd模板题

https://ac.nowcoder.com/acm/contest/5634/B

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll gcd(ll a,ll b)
{
    return b?gcd(b,a%b):a;

}
int main()
{
    ll a,b;
    string tmp;
    cin>>a>>b>>tmp;
    printf("%lld\n",gcd(a,b));
    return 0;
}