#include <bits/stdc++.h>
 
using namespace std;

int main(void) 
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  long long int b1,b2,b3;

  cin >> b1 >> b2 >> b3;

  long long int A = b3 - b2;
  long long int B = b2 - b1;

  //long double r = (A*1.0/B);
  //long double d = b3 - r*b2;
  //long long int d = b3 - ((A*b2)/B);
  //cout << ((A*b3)/B) + d << '\n';

  long long int D = b3 - b2;
  D*=A;
  D/=B;
  D+=b3;

  cout << D << '\n';
  
  return 0;
}