题解 | #字符个数统计#

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

// 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);
        while (scanner.hasNext()) {
            String str = scanner.nextLine();
            char[] ch=str.toCharArray();
            int count=0;
            Set<Character> set=new HashSet<Character>();
            for (char c:ch) {
                set.add(c);
            }
            System.out.println(set.size());
        }
    }
}