#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>


typedef long long int ll;
//#include<bits/stdc++.h>


using namespace std;







int main()
{

    int Q;
    Q = 1;
   // cin >> Q;

    while (Q--) {
        int a, b, c;
        cin >> a >> b >> c;
        if (a == b && b == c)cout << a << endl;
        else if (a == b && b != c)cout << c << endl;
        else if (a == c && b != c)cout << b << endl;
        else if (c == b && b != a)cout << a << endl;
        else if (a != b && a != c) {
            for (int i = 0; i <= 3; i++) {
                if (a != i) {
                    if (b != i) {
                        if (c != i) {
                            cout << i << endl;
                        }
                    }
                }
            }
        }

    }

    return 0;
}