/*
TASK:crossing
LANG:C++
*/
#include<iostream>
using namespace std;
int main()
{
    double a,b,s,w;
    cin>>w>>s>>a>>b;
    int t4=w/a+s/b;
    double ostmin=w/a+s/b-t4;
    ostmin*=60;
    int min=ostmin;
    int ostsec=(ostmin-min)*60;
    if(ostsec>60){min+=ostsec/60;ostsec=ostsec%60;}
    if(min>60){t4+=min/60;min=min%60;}
    cout<<t4<<':'<<min<<':'<<ostsec<<'\n';
    return 0;
}

