```cpp
#include<bits/stdc++.h>
using namespace std;
int s,v,q,h=8,m;
int main()
{
cin>>s>>v;
if(s%v==0){
q=s/v;
}
else{
q=s/v+1;
}
q+=10;
m-=q;
h-=abs(m)/60;
if(abs(m)%60!=0){
h--;
}
m=60-abs(m)%60;
if(h<0){
h=24+h;
}
if(h<10){
cout<<"0"<<h<<":";
}
else{
cout<<h<<":";
}
if(m<10){
cout<<"0"<<m;
}
else{
cout<<m;
}
return 0;
}
```
by li_yuchen @ 2023-04-16 16:39:26