// see
// http://www.inf.unibz.it/~calvanese/teaching/exams/ip-java/written-exams/computer-science/2005-02-02/spec-cs-6-cfu.html

public class LetterQueue {

    private String city;
    private String[] letters;
    private int firstfree;      // this is the first free position
                                // 0 ... firstfree - 1 are filled with letters

    public LetterQueue(String n, int s) {
        city = n;
        letters = new String[s];
        firstfree = 0;
    }


    public String getCity() {
        return city;
    }


    public int size() {
        return letters.length;
    }


    public void newLetter(String m) throws Exception {
        if (firstfree < letters.length) {
            letters[firstfree] = m;
            firstfree++;
        } else {
            throw new Exception();
        }
    }


    public String firstLetter() throws Exception {
        if (firstfree > 0) {
            return letters[0];
        } else {
            throw new Exception();
        }
    }


    public void removeLetter() throws Exception {
        if (firstfree > 0) {
            int j = 0;
            while (j < firstfree - 1) {
                letters[j] = letters[j + 1];
                j++;
            }
            firstfree--;
        } else {
            throw new Exception();
        }
    }


    public int numLetters() {
         return firstfree;
    }


    public String letter(int i) throws Exception {
         if (i >= 0 && i < firstfree) {
             return letters[i]; 
         } else {
            throw new Exception();
         }
    }

    public int[] shortLetters(int len) {

        int i;

        int count = 0;
        for (i = 0; i < firstfree; i++) {
            if (letters[i].length() < len) {
                count++;
            }
        }      

        int results[] = new int[count];

        int r = 0;
        for (i = 0; i < firstfree; i++) {
            if (letters[i].length() < len) {
                // we have found that mail number i is short

                results[r] = i;
                r++;
            }
        }      
        return results;

    }


    public static void main(String a[]) {
    try {


     LetterQueue q = new LetterQueue("Bolzano", 100);
     System.out.println(q.getCity() + ": " + q.numLetters() + " out of " + q.size());

     q.newLetter("Bersan: hello!");
     // 1 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 0 queued now

     q.newLetter("Foruzan: dont know");
     q.newLetter("Shogofa: bolzano is a green city");
     // 2 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 1 queued now

     q.newLetter("Lecha: let's party");
     // 2 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 1 queued now

     q.newLetter("Khuseyn: good bye");
     q.newLetter("Albert: big mountains");
     // 3 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 2 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 1 queued now

     System.out.println("delivered: " + q.firstLetter());
     q.removeLetter();
     // 0 queued now

     // the following should throw an exception
     q.removeLetter();

     } catch (Exception e) {
         System.out.println("got an exception while calling my letter methods...");
     }

    }
 

}