#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" };

const string ty_words[] =
  { "", "", "twenty", "thirty", "forty", "fifty",
    "sixty", "seventy", "eighty", "ninty" };

void say(const int n)
{ if (n>=0 && n<20)
  { print(small_names[n]); }
  
  else if (n<100)
  { const int dig1 = n / 10,
              dig2 = n % 10;
    print(ty_words[dig1]);
    if (dig2 != 0)
    { print("-");
      say(dig2); } }
  
  else if (n<1000)
  { const int dig1 = n / 100;
    const int digs23 = n % 100;
    say(dig1);
    if (digs23 == 0)
      print(" hundred");
    else
    { print(" hundred and ");
      say(digs23); } }

  else if (n < 1000000)
  { const int digs123 = n / 1000;
    const int digs456 = n % 1000;
    say(digs123);
    print(" thousand");
    if (digs456 != 0)
    { if (digs456 < 100)
        print(" and");
      print(" ");
      say(digs456); } }

  else if (n < 1000000000)
  { const int first6 = n / 1000000;
    const int last6 = n % 1000000;
    say(first6);
    print(" million");
    if (last6 != 0)
    { if (last6 < 100)
        print(" and");
      print(" ");
      say(last6); } }

  else if (n >= 1000000000)
  { const int first9 = n / 1000000000;
    const int last9 = n % 1000000000;
    say(first9);
    print(" billion");
    if (last9 != 0)
    { if (last9 < 100)
        print(" and");
      print(" ");
      say(last9); } }
  
  // no matter what I do after this point,
  // this function is guaranteed to work perfectly
  // for 0 to the maximum int value inclusive.

  else
  { print("minus ");
    say(- n); } }

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