#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
ll inf=1001001001001000000;
ll mod=1000000007;
int main(){
    ll a,b,c ;
    cin >> a >> b >> c ;
    if (a==b&&b==c)
    {
        cout << a << endl;
    }else if (a==b||a==c||b==c)
    {
        a^=b ;
        a^=c;
        cout << a << endl;
    }else{
        cout << 6-(a+b+c) << endl;
    }
}