题解 | #字符个数统计#

import java.util.*;

// 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.hasNextLine()) { // 注意 while 处理多个 case
            String line = in.nextLine();
            BitSet bs = new BitSet();
            for (int i = 0; i < line.length(); ++i) {
                int ascii = (int)line.charAt(i);
                if (ascii < 0 || ascii > 127) continue;
                else bs.set(ascii);
            }
            System.out.println(bs.cardinality());
            bs.clear();
        }
    }
}