#include <iostream>

using namespace std;

int main()
{
    int a,b,c;
    cout << "Enter numbers between -100 and 100 \n";
    cin >> a >> b >> c;
    if (a==b){
        cout << c;
    }else if (a==c){
        cout << b;
    }else{
        cout << a;
    }


    return 0;
}