#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  array<int, 3> a;
  rep(i, 3) cin >> a[i];
  sort(a.begin(), a.end());
  while (a[2] - a[0] > 2) {
    a[2] -= 2, a[0] += 1;
    sort(a.begin(), a.end());
  }
  cout << a[0] << endl;
  return 0;
}