import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

class Letter {
    private char value;

    public Letter(char value) {
        this.value = value;
    }

    public char getValue() {
        return value;
    }
}

class Word {
    private List<Letter> letters = new ArrayList<>();

    public Word(String input) {
        for (char c : input.toCharArray()) {
            letters.add(new Letter(c));
        }
    }

    public List<Letter> getLetters() {
        return letters;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Letter letter : letters) {
            sb.append(letter.getValue());
        }
        return sb.toString();
    }
}

class PunctuationMark {
    private char value;

    public PunctuationMark(char value) {
        this.value = value;
    }

    public char getValue() {
        return value;
    }
}

class Sentence {
    private List<Object> elements = new ArrayList<>();

    public Sentence(String input) {
        StringBuilder sb = new StringBuilder();
        for (char c : input.toCharArray()) {
            if (Character.isLetterOrDigit(c)) {
                sb.append(c);
            } else {
                if (sb.length() > 0) {
                    elements.add(new Word(sb.toString()));
                    sb.setLength(0);
                }
                elements.add(new PunctuationMark(c));
            }
        }
        if (sb.length() > 0) {
            elements.add(new Word(sb.toString()));
        }
    }

    public List<Object> getElements() {
        return elements;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Object element : elements) {
            if (element instanceof Word) {
                sb.append(((Word) element).toString());
            } else {
                sb.append(((PunctuationMark) element).getValue());
            }
        }
        return sb.toString();
    }
}

class Text {
    private List<Sentence> sentences = new ArrayList<>();

    public Text(String input) {
        StringBuilder sb = new StringBuilder();
        for (char c : input.toCharArray()) {
            if (c == '.' || c == '?' || c == '!' || c == ',') {
                sb.append(c);
                sentences.add(new Sentence(sb.toString()));
                sb.setLength(0);
            } else {
                sb.append(c);
            }
        }
        if (sb.length() > 0) {
            sentences.add(new Sentence(sb.toString()));
        }
    }

    public List<Sentence> getSentences() {
        return sentences;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (Sentence sentence : sentences) {
            sb.append(sentence.toString());
        }
        return sb.toString();
    }
}

public class Lab5 {
    public static void main(String[] args) {
        int C17 = 2430 % 17;
        System.out.println("\n---------------------------------------------------------------------------------------------------------------------");
        System.out.println("  C17 = " + C17 + ", So, the task is:  delete all previous occurrences of the last letter of each word of the specified text.");
        System.out.println("---------------------------------------------------------------------------------------------------------------------");

        Scanner scanner = new Scanner(System.in);
        boolean isDone = false;
        while (!isDone) {
            System.out.print("\nEnter a string or type 'q' to quit: ");
            String input = scanner.nextLine().trim();
            if (input.equals("q")) {
                System.out.print("\n The work is completed.");
                isDone = true;
            } else if (input.isEmpty()) {
                System.out.println("Error: Input string is empty. Please enter a non-empty string.");
            } else {
                try {
                    StringBuilder sb = new StringBuilder(input);
                    String[] words = sb.toString().split("\\s+");
                    for (int i = 0; i < words.length; i++) {
                        String word = words[i];
                        char lastChar = word.charAt(word.length() - 1);
                        if (!Character.isLetterOrDigit(lastChar)) {
                            int lastLetterIndex = -1;
                            for (int j = word.length() - 2; j >= 0; j--) {
                                if (Character.isLetter(word.charAt(j))) {
                                    lastLetterIndex = j;
                                    break;
                                }
                            }
                            if (lastLetterIndex != -1) {
                                char lastLetter = word.charAt(lastLetterIndex);
                                String newWord = "";
                                for (int j = 0; j < word.length() - 1; j++) {
                                    if (!Character.isLetterOrDigit(word.charAt(j)) || word.charAt(j) != lastLetter) {
                                        newWord += word.charAt(j);
                                    }
                                }
                                newWord += lastChar;
                                words[i] = newWord;
                            }
                        } else {
                            char lastLetter = lastChar;
                            String newWord = "";
                            for (int j = 0; j < word.length() - 1; j++) {
                                if (!Character.isLetterOrDigit(word.charAt(j)) || word.charAt(j) != lastLetter) {
                                    newWord += word.charAt(j);
                                }
                            }
                            newWord += lastLetter;
                            words[i] = newWord;
                        }
                    }
                    System.out.print("\n Final string: ");
                    System.out.println(String.join(" ", words));
                } catch (Exception e) {
                    System.out.println("An error occurred: " + e.getMessage());
                }
            }
        }
    }
}