#include <bits/stdc++.h>
#include <regex>
using namespace std;
using ll = int64_t;
#define all(c) c.begin(),c.end()
#define rall(c) c.rbegin(),c.rend()

// -------------------------------
// 2022/5/20 Hiroyuki Yamanouchi
// AtCoder Rating 187 10級
// -------------------------------

// void chmax(ll& a, ll b){ if(a < b) a = b; }
// void chmin(ll& a, ll b){ if(a > b) a = b; }
// for (int i = 0; i < N; i++){    
//      cin >> P[i];
// }


int main() {
 
    vector<int> A(3);
    cin >> A[0] >> A[1] >> A[2] ;

    int ans;

    if (A[0] == A[1] && A[1] == A[2]) ans = A[0];
    else if (A[0] == A[1] && A[1] != A[2]) ans = A[2];
    else if (A[0] != A[1] && A[1] == A[2]) ans = A[0];
    else if (A[0] == A[2] && A[1] != A[2]) ans = A[1];
    else if (A[0] != A[1] && A[1] != A[2]) ans = 6 -(A[0]+A[1]+A[2]);

    cout << ans << endl;
    
    return 0;
}