Template-gcd

• example

#include<iostream>
using namespace std;

typedef long long ll;

ll gcd(ll a, ll b) {
    
     return !b ? a : gcd(b, a % b); }

int main() {
    
    

	ll a, b;
	cin >> a >> b;

	cout << gcd(a, b);
	return 0;
}