#include <stdio.h>
#include <math.h>
int main ()
{
    int s,v,HH,MM;
    scanf ("%d%d",&s,&v);
    int t=ceil(1.0*s/v)+10;
    if (t<=480){
        HH=8-ceil(1.0*t/60);
        MM=60-t%60;
        printf("%.2d:%.2d",HH,MM);
    }
    else {
        HH=24+8-ceil(1.0*t/60);
        MM=60-t%60;
        printf (".2%d:%.2d",HH,MM);
        }
        return 0;
    }