#include <library.h>

const string small_names[] =
  { "zero", "one", "two", "three", "four", 
    "five", "six", "seven", "eight", "nine", 
    "ten", "eleven", "twelve", "thirteen", "fourteen", 
    "fifteen", "sixteen", "seventeen", "eighteen", "nineteen" };

void say(const int n)
{ if (n>=0 && n<20)
  { print(small_names[n]); }

  // no matter what I do after this point,
  // this function is guaranteed to work perfectly
  // for 0 to 19 inclusive.

  else
  { print("I don't know how to say ");
    print(n);
    print(" yet"); } }

void main()
{ while (true)
  { print("number? ");
    const int x = read_int();
    say(x);
    new_line(); }
  print("Bye!\n"); }