题解 | #字符个数统计#

import java.util.Scanner;
import java.util.HashSet;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String string = scanner.nextLine();

        char[] array = string.toCharArray();
        HashSet<Character> set = new HashSet<>();
        for (char c : array) {
            if (!set.contains(c) && (c >= 0 && c <= 127)) {
                set.add(c);
            }
        }
        System.out.println(set.size());
    }
}