#include <bits/stdc++.h> using namespace std; using i64 = long long; int main() { i64 x, y, z; cin >> x >> y >> z; i64 zz = min(z, abs(x - y)); z -= zz; i64 a = min(x, y); i64 b = max(x, y); cout << min(b, a + zz) + z / 2 << endl; }