C++六十分求助！

#include <iostream>
using namespace std;
int main()
{
	int x,n;
	cin >> x >> n;
	int sum;
	for (int i = x; i <= x + n; i++)
	{
		if (i % 6 == 0 || i + 1 % i == 0 || i % 7 == 0 || i + 1 % i == 0)
			continue;
		else
			sum += 250;
	}
	cout << sum;
	return 0;
}