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

void _main()
{
    int a, b, c;
    cin >> a >> b>> c;

    if (a != b and b != c and c != a)
        cout << 6 - a - b - c << '\n';
    
    else if (a == b and b == c)
        cout << a << '\n';

    else
        cout << (a == b ? c : a == c ? b : a) << '\n';
    return;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(15);
    _main();
}