题解 | #字符个数统计#

import java.util.HashMap;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String s = sc.nextLine();
        HashMap<Character, Integer > map = new HashMap<>();
        for (int i = 0; i < s.length(); i ++) {
            Character c = s.charAt(i);
            //A-Z,65-90;a-z,97-122
            if (c >= 0 && c <= 127 ) {
                //get is key, not value
                if (map.get(c) != null) {
                    continue;
                } else {
                    map.put(c, i);
                }
            }
        }
        System.out.println(map.size());
    }
}