#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using llu = long long unsigned;

vector<ll> dx = { 0, 0, -1, 1};
vector<ll> dy = {-1, 1,  0, 0};

#define MOD 1000000007
int main() {
    int X, Y, Z;
    cin >> X >> Y >> Z;

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