/* -*- coding: utf-8 -*-
 *
 * 920.cc:  No.920 あかあお - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

/* global variables */

/* subroutines */

/* main */

int main() {
  int x, y, z;
  scanf("%d%d%d", &x, &y, &z);

  if (x < y) {
    int d = min(y - x, z);
    x += d, z -= d;
  }
  if (x > y) {
    int d = min(x - y, z);
    y += d, z -= d;
  }

  x += z / 2, y += z / 2;

  printf("%d\n", min(x, y));
  return 0;
}