import std.algorithm, std.array, std.container, std.range;
import std.string, std.conv, std.bigint, std.math, std.random;
import std.stdio, std.typecons;

const auto max = 10 ^^ 7;

void main()
{
  auto rgb = readln.split.map!(to!int);

  bool calc(int i, int _)
  {
    auto a = rgb.map!(x => x - i);
    auto b = a.filter!(x => x > 0).map!(x => x / 2).sum;
    auto c = a.filter!(x => x < 0).map!(x => -x).sum;
    return b >= c;
  }

  auto r = iota(max + 1).map!(to!int).assumeSorted!(calc).lowerBound(0);
  writeln(r.back);
}