#include<iostream>
#include<iomanip>
#include<math.h>
#include<vector>
#include<algorithm>
#include<string>
#include<queue>
#include<stack>
#include<set>
#include<map>
#define EPS 1e-6
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef long double ld;

int main() {
	ll b1, b2, b3;
	cin>>b1>>b2>>b3;
	long double r, d;
	r = (b2 - b3) / (long double)(b1 - b2);
	d = b2 - r * b1;
	long double res = r * b3 + d;
	if(res >= 0) cout<<(ll)(res + EPS)<<endl;
	else cout<<(ll)(res - EPS)<<endl;
}