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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>
#define LP pair<ll, ll>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define all(s) s.begin(), s.end()
#define rall(s) s.rbegin(), s.rend()
template<class T>
void chmax(T& a, T b) { a = max(a, b); };
template<class T>
void chmin(T& a, T b) { a = min(a, b); };

int main() {
  int a, b, c;
  cin >> a >> b >> c;
  if (a == b && b== c) cout << a << endl;
  else if (a != b && b != c && c != a) cout << 6-(a+b+c) << endl;
  else if (a == b) cout << c << endl;
  else if (b == c) cout << a << endl;
  else if (c == a) cout << b << endl;
  return 0;
}