#include <iostream>
#include <cstdlib>
#include <math.h>
#include <string>
using namespace std;

int main() {
	double r, k, m;
	int i, s, n, p, u;
	cin >> s;
	cin >> m;
	cin >> n;
	p = 0;
	for (i = 0; i < 100; i++) {
		p = p + 1;
		r = p / 100.;
		k = (s * r * pow(1 + r, n)) / (12 * (pow(1 + r, n) - 1));
		if (abs(m - k) < 0.1)
			u = p;
	}
	cout << u;
	cin.get(); cin.get();
	return 0;
}