#include<stdio.h>
int main()
{
	long long int a, b, c;
	scanf("%lld %lld %lld", &a, &b, &c);
	long long int ans[2], aa = 0;
	if (c <= b)
	{
		if (c % a == 0)
		{
			ans[aa] = c / a;
			aa++;
		}
		if ((c + b) % a == 0)
		{
			ans[aa] = (b + c) / a;
			aa++;
		}
	}
	else
	{
		if ((b + c) % a == 0)
		{
			ans[aa] = (b + c) / a;
			aa++;
		}
	}
	if (aa == 0)
	{
		ans[aa] = -1;
		aa++;
	}
	for (a = 0; a < aa; a++)
		printf("%lld\n", ans[a]);
}