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

template <typename T, typename U> void cmin(T &a, U b) {
  if (a > b) a = b;
}
template <typename T, typename U> void cmax(T &a, U b) {
  if (a < b) a = b;
}

signed main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);

  long R, G, B;
  cin >> R >> G >> B;

  auto f = [&](long mid) {
    long r = 0, g = 0, b = 0, ng = 0;
    (R < mid) ? ng += mid - R : r += R - mid;
    (G < mid) ? ng += mid - G : g += G - mid;
    (B < mid) ? ng += mid - B : b += B - mid;
    if (r / 2 + g / 2 + b / 2 >= ng) return true;
    else return false;
  };
  long ok = 0, ng = 1e9;
    while (ng - ok > 1) {
      long mid = (ok + ng) / 2;
      (f(mid)) ? ok = mid : ng = mid;
    }
  cout << ok << "\n";
}