#include "library.h"

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

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

void say(const int n)
{ 
  if (n < 0)
  { cout << "minus ";
    say(- n); }
  else if (n < 20)
    cout << Small[n];
  else if (n%10 == 0 && n<100)
    cout << tynumber[n/10 - 2];
  else if (n >= 20 && n < 100)
  { const int first = n /10 * 10,
              second = n % 10;
    say(first);
    cout << "-";
    say(second); }
  else if (n < 1000)
  { const int first = n / 100;
    const int second = n % 100;
    say(first);
    cout << " hundred";
    if (second > 0)
    { cout << " and ";
      say(second); } }
  else if (n < 1000000)
  { const int first = n / 1000;
    const int second = n % 1000;
    say(first);
    cout << " thousand";
    if (second > 0)
    { cout << " ";
      say(second); } }
  else if (n < 1000000000)
  { const int first = n / 1000000;
    const int second = n % 1000000;
    say(first);
    cout << " million";
    if (second > 0)
    { cout << " ";
      say(second); } }
  else
  { const int first = n / 1000000000;
    const int second = n % 1000000000;
    say(first);
    cout << " billion";
    if (second > 0)
    { cout << " ";
      say(second); } }
}

bool want_to_go_again()
{ while (true)
  { cout << "Do you want to go again? ";
    const string s = read_string();
    if (s == "yes")
      return true;
    if (s == "no")
      return false; } }

void main()
{ while (true)
  { print("Enter a number: ");
    const int n = read_int();
    say(n);
    new_line();
    if (! want_to_go_again())
      break; }
  cout << "End of program\n"; }