/*
TASK:crossing
LANG:c++
*/
#include <iostream>
using namespace std;
double w,s,a,b,sum;
int suma;
void in()
{
     cin >> s >> w >> a >> b;
s*=1000;
w*=1000;
a/=3.6;
b/=3.6;
}

void solve()
{  
     sum=s/a+w/b;
     suma=sum;
}
void out()
{
 int ar,av,al;
 ar=0;
 av=0;
 al=0;
 ar=suma/3600;suma=suma%3600;
 av=suma/60;
 al=suma%60;
 cout << ar << ":" << av << ":" << al << "\n";
}
int main()
{
    in();
    solve();
    out();
    return 0;
    /* Pinball > you.By dah Troll*/
}     
  
     
     


     
     
        
