#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
const ll N_MAX = 2e5;

int main(){
    ll a, b, c;
    cin >> a >> b >> c;

    ll ans = 0^1^2^3;
    if(a == b && b == c){
        cout << a << endl;
    }else if(a != b && b != c && c != a){
        cout << (ll)(ans^a^b^c) << endl;
    }else{
        vector<ll> cnt(4, 0);
        cnt[a]++;
        cnt[b]++;
        cnt[c]++;
        rep(i, 4) if(cnt[i] == 1){
            cout << i << endl;
            return 0;
        }
    }
}