#include <iostream>

using namespace std;

int main()
{
   int a, b,c;
    cin >>a>>b>>c;
    if(a!=b && a!=c){
        cout<<a<<endl;
        }else if(b!=a&& b!=c){
            cout<<b<<endl;

        } else{

            cout<<c<<endl;
        }
    return 0;
}
