#include<stdio.h>
int main()
{
    int s,v,min,hour,min2;
    scanf("%d %d",&s,&v);
    min=s/v+10;
    hour=7-min/60;
    min2=59-min%60;
    if(min==480)
        {printf("00:00");
    return 0;}
    if(hour>=0)
    {
        if(min2>=10)
            printf("0%d:%d",hour,min2);
        else printf("0%d:0%d",hour,min2);
    }
    else if(hour+24>=10)
    {
        if(min2>=10)
            printf("%d:%d",hour+24,min2);
        else printf("%d:0%d",hour+24,min2);
        }
    else  if(min2>=10)
        printf("0%d:%d",hour+24,min2);
    else printf("0%d:0%d",hour+24,min2);
        return 0;
}