题解 | #字符个数统计#

import java.util.Scanner;

// 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 sc = new Scanner(System.in);
        String s = sc.nextLine();

        int[] arr = new int[128];

        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            arr[c] = 1;
        }
        int count = 0;
        for (int i : arr) {
            if (i == 1) {
                count++;
            }
        }
        System.out.println(count);
    }
}