#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
using namespace std;

using ll = long long;
const int INF = 1e9;
const ll inf = 1LL<<60;

void solve() {
  int a, b, c; cin >> a >> b >> c;
  cout << (a^b^c) << '\n';
}

int main() {
  ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  // int t; cin >> t;
  /*while (t--)*/ solve();
}