题解 | #字符个数统计#

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        HashSet<Character> set = new HashSet<>();
        for(int i = 0; i < str.length();i++){
            set.add(str.charAt(i));
        }
        System.out.print(set.size());
    }
}