public static String pangrams(String s) {
        
        Set<Character> chars = new HashSet<>();
        
        for (char c : s.toLowerCase().toCharArray()) {
            if (c >= 'a' && c <= 'z') {
                chars.add(c);    
            }
        }
        
        return chars.size() == 26 ? "pangram" : "not pangram";
    }