#include <bits/stdc++.h>
using namespace std;
long long c[3];
int main() {
  for (int k = 0; k < 3; k++) cin >> c[k];
  sort(c, c + 3);
  if ((c[1] - c[0]) % 2 == 0)
    cout << c[1] << endl;
  else
    cout << c[2] << endl;
  return 0;
}
