#include<stdio.h>
#include<math.h>
#define ot 8*60
#define gc 10
int main()
{
    int s,v;
    double t,t1;
    scanf("%d %d",&s,&v);
    t=s/v+gc;
    t1=ot-t;
    while(t1<0)
    {
        t1+=24*60;
    }
    int hour=(int)floor(t1/60);
    int min=(int)t1%60-1;
    printf("%02d:%02d",hour,min);
    return 0;
}