Pangram

import java.util.HashSet;
public class PangramChecker {

public boolean isPangram(String input) {
    HashSet<Character> letters = new HashSet<>();
    for(char letter: input.toLowerCase().toCharArray()){
        if(Character.isLetter(letter)){
            letters.add(letter);
        }
    }
    return letters.size() >=26;
}

}