#include <stdio.h>
int main()
{
    int s,v;
    int t,h,m;
    scanf("%d %d",&s,&v);
    t = 24 * 60 + 8 * 60 - (s+v-1)/v - 10;
    h = t / 60;
    m = t % 60;
    if (h>24)
    {
        h -= 24;
    }
    printf("%02d:%02d\n",h,m);
    return 0;
}