/*
TASK:crossing
LANG:C++
*/
#include <iostream>
using namespace std;
int main()
{
    int ti,h,min,sec;
    double t,w,s,a,b;
    cin >> w >> s >> a >> b;
    t=(w/a)+(s/b);
    t=t*60;
    ti=t;
    if (ti > t) ti=ti-1;
    if (ti == t) ti=ti;
    h=(ti/60);
    min=(ti%60);
    sec=(t-ti);
    cout << h << ":" << min << ":" << sec;
return 0;
}
