#include <bits/stdc++.h>
#define int long long 
using namespace std;


signed main() {
  int X, Y, Z;
  cin >> X >> Y >> Z;
  int ans = 0;
  if( abs( X-Y ) <= Z ){
    Z -= abs( X-Y );
    ans += max(X, Y);
    ans += Z/2;
    cout << ans << endl;
  }else{
    cout << min(X+Z, Y+Z) << endl;
  }
  
}