请问下输入在for内和for外有什么区别阿，为什么在for外会报错呢

#include<iostream>
using namespace std;
int main() {
	int day, mom, school, max = 0, sum,unhappy=0;

	for (day = 1;day <= 7;day++)
	{
cin >> school >> mom;
		sum = mom + school;
		if ((sum > 8 )&& (sum > max))
		{
			
			max = sum;
			unhappy = day;
			
		}
	}
	cout << unhappy << endl;
	system("pause");
	return 0;
}

#include<iostream>
using namespace std;
int main() {
	int day, mom, school, max = 0, sum,unhappy=0;
cin >> school >> mom;
	for (day = 1;day <= 7;day++)
	{

		sum = mom + school;
		if ((sum > 8 )&& (sum > max))
		{
			
			max = sum;
			unhappy = day;
			
		}
	}
	cout << unhappy << endl;
	system("pause");
	return 0;
}