#include<stdio.h>   
int main(){
    int v, s, t, hour, min;
    scanf("%d %d", &s, &v);
    if(s % v == 0){
        t = s / t;
    }else{
        t = s / v + 1;
    }
    if(7 - (t + 10) / 60 >= 0){
        hour = 7 - (t + 10) / 60;
    }else{
        hour = 31 - (t + 10) / 60;
    }
    
    min = 60 - (t + 10) % 60;
    printf("%02d:%02d", hour, min);
    return 0;
}