#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
  int X,Y,Z;
  cin>>X>>Y>>Z;
  if(X < Y) swap(X,Y);
  if(X-Y > Z){
      Y += Z;
      Z = 0;
  }
  else{
      Z -= X-Y;
      Y = X;
  }
  cout<<min(X,Y)+Z/2<<endl;
}