#include <iostream>

using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int a, b, c;
    if (cin >> a >> b >> c) {
        if (a == b) {
            cout << c << "\n";
        } else if (a == c) {
            cout << b << "\n";
        } else {
            cout << a << "\n";
        }
    }

    return 0;
}