#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <stack>

using namespace std;

#define reps(i, a, n) for (int i = (a); i < (int)(n); ++i)
#define rep(i, n) reps(i, 0, n)

#define ALL(x) x.begin(),x.end() 
#define SIZE(x) ll(x.size()) 

#define INF32 2147483647 //2.147483647×10^{9}:32bit整数のinf
#define INF64 9223372036854775807 //9.223372036854775807×10^{18}:64bit整数のinf
#define MOD 1000000007 //問題による


#define F first
#define S second

#define coutALL(x) for(auto i=x.begin();i!=--x.end();i++)cout<<*i<<" ";cout<<*--x.end()<<endl;
#define coutALL2d(vv) for(const auto& v : vv){for(const auto& e : v){cout << e << " ";}cout << endl;}

#define vi vector<int>
#define vvi vector<vector<int> >
#define vll vector<long long>
#define vvll vector<vector<long long> >


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{
        int res;
        if(a==b) res = c;
        else if(b==c) res = a;
        else if(a==c) res = b;
        cout << res << endl;
    }
    
}