#include<stdio.h>
int main(){
    int s,v,H=7,M=60,h,m;
    scanf("%d %d",&s,&v);
    double t1=s/v*1.0;
    int t=s/v;
    if(t1!=t){
        t++;
    }
    if(t>50){
        int z=(t-50)/60;
        m=(t-50)%60,h=1+z;
    }else{
        m=t,h=0;
        M=50;
    }
    if(h>7){
        h-=7,H=24;
    }
    printf("%.2d:%.2d",H-h,M-m);
    return 0;
}