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

using ll = long long;
using VI = vector<int>;
using VVI = vector<vector<int>>;
using VVVI = vector<vector<vector<int>>>;
using VL = vector<ll>;
using VVL = vector<vector<ll>>;
using VVVL = vector<vector<vector<ll>>>;
using VD = vector<double>;
using VVD = vector<vector<double>>;
using VVVD = vector<vector<vector<double>>>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using P = pair<int, int>;
using VP = vector<P>;

#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define FOR(i, a, b) for (ll i = a; i < (ll)(b); i++)
#define ALL(a) (a).begin(),(a).end()

constexpr int INF = 1001001001;
constexpr ll LINF = 1001001001001001001ll;
constexpr int DX[] = {1, 0, -1, 0};
constexpr int DY[] = {0, 1, 0, -1};

template< typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true); }
template< typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true); }

const ll MOD = 998244353;

ll mod_pow(ll x, ll n, ll mod) {
    ll res = 1;
    while (n > 0) {
        if (n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

int main() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int a, b, c;
    cin >> a >> b >> c;
    if (a == b && b == c) {
        cout << a << endl;
        return 0;
    }
    if (a == b) {
        cout << c << endl;
        return 0;
    }
    if (a == c) {
        cout << b << endl;
        return 0;
    }
    if (c == b) {
        cout << a << endl;
        return 0;
    }
    cout << 6 - a - b - c << endl;
}