题解 | #字符个数统计#

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        int[] charNum = new int[128];
        for (char c : str.toCharArray()) {
            charNum[c]++;
        }
        int sum = 0;
        for (int i : charNum) {
            if (i != 0) {
                sum++;
            }
        }
        System.out.println(sum);
    }
}