#include <bits/stdc++.h>
using namespace std;
#define int long long
constexpr int inf = 1e18;
constexpr int maxn = 2e5 + 5;
constexpr int mod = 998244353;

inline void solve()
{
  int a, b, c; cin >> a >> b >> c;
  int x = 0 ^ 1 ^ 2 ^ 3;
  x ^= a;
  x ^= b;
  x ^= c;
  cout << x << '\n';
}

signed main()
{
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  solve();
  return 0;
}
/*
The details you should care:

*/