#include <stdio.h>

#if __linux__
  #define OS_IS_1 "Linux"
#elif __APPLE__
  #define OS_IS_1 "Mac OS"
#else
  #define OS_IS_1 "Unknown OS"
#endif

#if __linux
  #define OS_IS_2 "LINUX"
#elif __MACH__
  #define OS_IS_2 "MAC OS"
#else
  #define OS_IS_2 "UNKNOWN OS"
#endif


int main (void)
{
  printf ("1. OS is   =[%s]\n", OS_IS_1);
  printf ("2. OS is   =[%s]\n", OS_IS_2);

  return 0;
}