#define _GNU_SOURCE 1

#include <stdio.h>
#include <string.h>
#include <iostream>

struct S
{
  S () : end (buffer) {}

  ~S ()
  {
    fwrite_unlocked (buffer, end - buffer, 1, stdout);
  }

#if VERSION == 3
  void __attribute__((noinline))
#else
  void
#endif
  write (const char *x, size_t len)
  {
    if (__builtin_expect (buffer + sizeof (buffer) - end < len, 0))
      {
	fwrite_unlocked (buffer, end - buffer, 1, stdout);
	end = buffer;
      }
    memcpy (end, x, len);
    end += len;
  }

#if VERSION == 1 || VERSION == 3
  template <size_t N>
  void
  write (const char (&x)[N])
  {
    write (x, N - 1);
  }
#elif VERSION == 2
  template <size_t N>
  void __attribute__((noinline))
  write (const char (&x)[N])
  {
    write (x, N - 1);
  }
#else
  void __attribute__((noinline))
  write (const char *x)
  {
    write (x, strlen (x));
  }
#endif
  char buffer[4096];
  char *end;
};

int
main ()
{
  S s;
  for (int i = 0; i < 100000000; ++i)
    {
#if VERSION <= 4
      s.write ("Hello!");
#elif VERSION == 5
      fputs_unlocked ("Hello!", stdout);
#elif VERSION == 6
      fwrite_unlocked ("Hello!", 6, 1, stdout);
#elif VERSION == 7
      std::cout << "Hello!";
#else
#error Please define VERSION
#endif
    }
  return 0;
}