```cpp
#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
int main() {
double s,v;
scanf("%lf%lf",&s,&v);
int c=ceil(s/v)+10;
int ji;
if(c>480) {
ji=480-c+1440;
} else {
ji=480-c;
}
int shi=ji/60,fen=ji%60;
printf("%02d:%02d",shi,fen);
return 0;
}
```
by Moco_jof @ 2024-09-15 16:22:57
因为你定的$m=50$，当（s/v+1）%60>50时m就变成负数了
by noip_ioi_luck @ 2024-09-15 16:24:41
@[noip_ioi_luck](/user/679549) @[Moco_jof](/user/1204055) 谢谢
by AAAAA114514AAAAA @ 2024-09-15 16:46:16