还是类大佬（bushi

#include<iostream>
#include<cmath>
using namespace std;

class _time{
public:
	_time();
	_time(int, int);

	void operator=(_time);
	void operator+=(_time);
	void operator-=(_time);

	void print();
	void carry();

	int hour;
	int minute;
private:

};

_time::_time(){
	hour = 0;
	minute = 0;
}

_time::_time(int h, int m) {
	hour = h;
	minute = m;
}

void _time::print() {
	if (hour < 10) {
		cout << '0';
	}
	cout << hour<<':';
	if (minute < 10) {
		cout << '0';
	}
	cout << minute;
}

void _time::carry() {
	hour += minute / 60;
	minute %= 60;
}

void _time::operator=(_time t) {
	hour = t.hour;
	minute = t.minute;
}

void _time::operator+=(_time t) {
	hour += t.hour;
	minute += t.minute;
	hour += minute / 60;
	minute %= 60;
}

void _time::operator-=(_time t) {
	hour -= t.hour;
	minute -= t.minute;
	if (minute < 0) {
		minute += 60;
		hour--;
	}
	if (hour < 0) {
		hour += 24;
	}
}

int main() {
	double s, v;
	cin >> s >> v;

	int t = ceil(s / v);
	_time t1(0,t);
	t1.carry();
	_time school(8, 0);
	_time ljfl(0, 10);
	
	school -= ljfl;
	school -= t1;
	school.print();

	return 0;
}