백준 24313 c++

#include <iostream>

using namespace std;

int input(int lower, int upper);

int main(void)
{
	int a1, a0, c, n0, n;
	int f, g;

	a1 = input(-100, 100);
	a0 = input(-100, 100);
	c = input(1, 100);
	n0 = input(1, 100);
	if (a1 * n0 + a0 <= c * n0 && c >= a1)
	{
		cout << "1" << endl;
	}
	else
	{
		cout << "0" << endl;
	}


	return 0;
}

int input(int lower, int upper)
{
	int A;

	while (1)
	{
		cin >> A;
		if (A >= lower && A <= upper)
		{
			break;
		}
		else
		{
			;
		}
	}

	return A;
}