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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        // while (in.hasNextInt()) { // 注意 while 处理多个 case
        //     int a = in.nextInt();
        //     int b = in.nextInt();
        //     System.out.println(a + b);
        // }
        String line = in.nextLine();
        char[] arr = new char[128];
        int index = 0;
        for (int i = 0; i < line.length(); i++) {
            char c = line.charAt(i);
            if (index == 0) {
                arr[0] = c;
                index++;
                continue;
            }
            boolean has = false;
            for (int j = 0; j < index; j++) {
                if (arr[j] == c) {
                    has = true;
                    break;
                }
            }
            if (has) {
                continue;
            } else {
                arr[index] = c;
                index++;
            }
        }
        System.out.println(index);
    }
}