/*
TASK:crossing
LANG:C++
*/
#define INF 1<<15

#include <iostream>
#include <cmath>

double w, s, a, b, t, x, min;

int main()
{
    scanf("%lf%lf%lf%lf", &w, &s, &a, &b);
    
    min=INF;
    
    for (x=0; x<=s/2; x+=0.01)
        {
              t=w*w/4;
              t+=x*x;
              t=sqrt(t);
              t/=a;
              
              t+= ((s/2)-x) / b;
              
              if(t<min) min=t;
        }
    
    min*=2;
    
    printf("%d:", (int)min);
    min-=(int)min;
    min*=60;
    
    printf("%d:", (int)min);
    min-=(int)min;
    min*=60;
    
    if ( (min-(int)min)>=0.5 ) printf("%d", (int)min+1);
       else printf("%d", (int)min);
    
    printf("\n");
    
return 0;
}

