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

int main() {
	int x, y, z, p;
	cin >> x >> y >> z;

	int n = max(x, y) - min(x, y);
	if (n) {
		if (n > z) {
			p = min(x, y) + z;
			cout << p << endl;
			return 0;
		}
		else {
			z -= n;
			int s = z / 2;
			p = max(x, y) + s;
			cout << p << endl;
			return 0;
		}
	}
	else {
		int s = z / 2;
		p = max(x, y) + s;
		cout << p << endl;
	}
}