题解 | #字符个数统计#

import java.io.; import java.util.;

public class Main{ public static void main(String [] args) throws Exception{ BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));

    char [] arr  = bf.readLine().toCharArray();
    Set set = new HashSet();
    for(int i = 0; i< arr.length; i++){
        set.add(arr[i]);
    }
    System.out.println(set.size());
}

}