题解 | #字符个数统计#

public class Main{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        HashSet hs = new HashSet();
        
        String str = sc.nextLine();
        for(char c:str.toCharArray()){
            hs.add(c);
        }
        System.out.println(hs.size());
    }
}