#include <iostream>
using namespace std;

int main(void){
  double b1,b2,b3,ans;
  cin>>b1>>b2>>b3;
  ans=(b3*(b3-b2)/(b2-b1))+b2-(b1*(b3-b2)/(b2-b1));
  int a=ans;
  cout<<a<<endl;
  return 0;
}