#include <bits/stdc++.h>
#define nl '\n'
#define ll long long
#define all(c) c.begin(),c.end()
#define print(c) for(auto e : c) cout << e << " "; cout << nl
using namespace std;

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

    vector<int> a(3);
    for(auto &e : a) cin >> e;

    if((a[0] & 1 == a[1] & 1)) cout << a[2] << nl;
    else if((a[0] & 1) == (a[2] & 1)) cout << a[1] << nl;
    else cout << a[0] << nl;

    return 0;
}