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

int main(){
  int a, b, c;
  cin >> a >> b >> c;
  if(a == b) cout << c;
  else if(b == c) cout << a;
  else if(c == a) cout << b;
  else cout << 0;
  return 0;
}
#include <bits/stdc++.h>

int main(){
    int V, T, S, D;
    std::cin >> V >> T >> S >> D;
    
    int begin = V * T;
    int end = V * S;
    
    if(D >= begin && D <= end){
        std::cout << "No" << std::endl;
    }else{
        std::cout << "Yes" << std::endl;
    }
    
    return 0;
}

