题解 | #字符个数统计#

import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String str = reader.readLine();
        int res = 0;
        boolean[] arr = new boolean[127];
        char[] cs = str.toCharArray();
        for(char c : cs){
            if(!arr[c]){
                res++;
                arr[c] = true;
            }
        }
        System.out.println(res);
    }
}