#include <iostream>
#include <cassert>
#include <map>

using namespace std;

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

  map<int, int> mp;
  for (int i = 0; i < 3; i++) {
    int a; cin >> a;
    mp[a]++;
  }

  if (mp.size() == 3) {
    for (int i = 0; i < 3; i++) {
      if (mp[i] == 0) {
	cout << i << endl;
      }
    }
  } else if (mp.size() == 1) {
    cout << mp.begin()->first << endl;
  } else {
    for (auto &[a, b]: mp) {
      if (b == 1) cout << a << endl;
    }
  }
  return 0;
}