Add two Fractions(3.0)

#include<iostream>
#include<algorithm>
using namespace std;

void addFraction(int num1, int den1, int num2,int den2){
    long long int gcd = __gcd(den1, den2);
    long long int lcm = ((den1*den2)/ gcd);
    long long int upper_half = ((lcm / den1)* num1+(lcm / den2)* num2);

    long long int k = __gcd(upper_half, lcm);

    cout << upper_half/k << '/' << lcm/k << endl;
}

int main(){
    int t; cin >> t;
    while(t--){
        int a, b, c, d;
        cin >> a >> b >> c >> d;
        addFraction(a, b, c, d);
    }
    return 0;
}