#include <iostream>
using namespace std;
int main() {
	int m, t, s;
	cin >> m >> t >> s;
	if (t != 0) {
		if (s % t == 0) {
			m -= s / t;
		} else
			m = m - s / t - 1;
	} else {
		m -= s;
	}
	if (m < 0)
		cout << 0;
	else
		cout << m;
}