#include <stdio.h>
using namespace std;

int main()
{
    int s,v;
    scanf("%d%d",&s,&v);
    int h=7,m=50;
    int t;
    if(s%v==0)
        t=s/v;
    else 
        t=s/v+1;
    t%=24*60;
    h-=t/60;
    m-=t%60;
    printf("%02d:%02d",h,m);
    return 0;
}