string num2word(int n) {    
    string s;
    int t = n/10;
    int u = n%10;
    
    switch (t) {
        case 0:
            if (u == 0) return "zero";
            break;
        case 1: 
            switch (u) {
                case 0: s = "ten";       break;
                case 1: s = "eleven";    break;
                case 2: s = "twelve";    break;
                case 3: s = "thirteen";  break;
                case 4: s = "fourteen";  break;
                case 5: s = "quarter";   break;
                case 6: s = "sixteen";   break;
                case 7: s = "seventeen"; break;
                case 8: s = "eighteen";  break;
                case 9: s = "nineteen";  break; 
            }
            return s;
            break;
        case 2: s = "tweenty";   break;
    }
    switch (u) {
        case  1: s += " one";   break;
        case  2: s += " two";   break;
        case  3: s += " three"; break;
        case  4: s += " four";  break;
        case  5: s += " five";  break;
        case  6: s += " six";   break;
        case  7: s += " seven"; break;
        case  8: s += " eight"; break;
        case  9: s += " nine";  break;
    }
    
    return ltrim(s);
}

string timeInWords(int h, int m) {
  string s;
  
 if (h == 0 && m == 0)  return "midnight";
 if (h == 12 && m == 0) return "noon";
 if (m == 30)           return "half past " + num2word(h);
 if (m == 15)           return "quarter past " + num2word(h);
 if (m == 45)           return "quarter to " + num2word(h+1);
 if (m == 0)            return num2word(h) + " o' clock";
 
  switch (m) {
      case 1:  s = " minute";   break;
      default: s = " minutes";  break;
  }
  
  if (m > 30)
    return num2word(60 - m) + s + " to " + num2word(h+1);
  return num2word(m) + s + " past " + num2word(h);  
}