题解 | #字符个数统计#

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s = scanner.nextLine();
        HashSet<Character> set = new HashSet<>();
        for (int i = 0; i < s.length(); i++) {
            set.add(s.charAt(i));
        }
        System.out.println(set.size());
    }
}