#include <iostream>
using namespace std;

int main()
{
    int a, b, c;
    cin >> a >> b >> c;
    if (a == b && b == c)
    {
        cout << a << endl;
        return 0;
    }
    if (a != b && b != c && a != c)
    {
        for (int i = 0; i < 4; i++)
        {
            if (i != a && i != b && i != c)
            {
                cout << i << endl;
                return 0;
            }
        }
    }
    if (a == b)
    {
        cout << c << endl;
        return 0;
    }
    if (c == b)
    {
        cout << a << endl;
        return 0;
    }
    if (c == a)
    {
        cout << b << endl;
        return 0;
    }
}