求大佬们看看90分有一个wa了

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

int main()
{
	int s = 0, v = 0,z;
	cin >> s >> v;
	if (s / v == 0) z = s / v;
	else z = s / v + 1;
	int rec1 = (z + 10) / 60;
	int rec2 = (z + 10) % 60;
	if (7 - rec1 >= 0)
	{
		if (60 - rec2 >= 10)
			printf("0%d:%d", 7 - rec1, 60 - rec2);
		else
			printf("0%d:0%d", 7 - rec1, 60 - rec2);
	}
	else
	{
		if (60 - rec2 >= 10)
			printf("%d:%d", 31 - rec1, 60 - rec2);
		else
			printf("%d:0%d", 31 - rec1, 60 - rec2);
	}
	return 0;
}