#include <iostream>
using namespace std;

int main(){
	double b[3];
	cin >> b[0] >> b[1] >> b[2];
	double r = (b[1] - b[2]) / (b[0] - b[1]), d = b[1] - r * b[0];
	cerr << r << ' ' << d << endl;
	cout << r * b[2] + d << endl;
}