Write a program to accept a sentence which may be terminated by either ‘.’, ‘?’ or ‘!’ only. The words may be separated by a single blank space and should be case-sensitive.

Perform the following tasks:
(a) Determine if the accepted sentence is a Pangram or not. A Pangram is a sentence that contains every letter of the alphabet at least once. Example: “The quick brown fox jumps over the lazy dog.”
(b) Display the first occurring longest and shortest word in the accepted sentence.

Test your program for the following data and some random data:

Example 1
INPUT: Pack my box with five dozen liquor jugs.
OUTPUT:
IT IS A PANGRAM
LONGEST WORD: liquor
SHORTEST WORD: my

Example 2
INPUT: THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG.
OUTPUT:
IT IS A PANGRAM
LONGEST WORD: QUICK
SHORTEST WORD: THE

Example 3
INPUT: Hello my World.
OUTPUT:
IT IS NOT A PANGRAM
LONGEST WORD: Hello
SHORTEST WORD: my

Example 4
INPUT: Alas! it failed#
OUTPUT: INVALID INPUT

import java.util.Scanner;
class Pangram{
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        System.out.print("Enter the sentence: ");
        String s = in.nextLine();
        if(s.length() == 0){
            System.out.println("INVALID INPUT");
            return;
        }
        char last = s.charAt(s.length() - 1);
        if(".?!".indexOf(last) == -1){
            System.out.println("INVALID INPUT");
            return;
        }
        String shortest = new String(s);
        String longest = new String();
        boolean isPangram = true;
        for(char ch = 'a'; ch <= 'z'; ch++){
            boolean match = false;
            for(int i = 0; i < s.length(); i++){
                if(ch == Character.toLowerCase(s.charAt(i))){
                    match = true;
                    break;
                }
            }
            if(!match){
                isPangram = false;
                break;
            }
        }
        if(isPangram)
            System.out.println("IT IS A PANGRAM");
        else
            System.out.println("IT IS NOT A PANGRAM");
        String word = new String();
        for(int i = 0; i < s.length(); i++){
            char ch = s.charAt(i);
            if(Character.isLetterOrDigit(ch))
                word += ch;
            else{
                if(word.length() > longest.length())
                    longest = new String(word);
                if(word.length() < shortest.length())
                    shortest = new String(word);
                word = new String();
            }
        }
        System.out.println("LONGEST WORD: " + longest);
        System.out.println("SHORTEST WORD: " + shortest);
    }
}