题解 | #字符个数统计#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String a = sc.nextLine();
            int sum = 0;
            Map<String, Integer> map = new LinkedHashMap<>();
            for (int i = 0; i < a.length(); i++) {
                if (a.charAt(i) >= (char) 0 && a.charAt(i) <= (char) 127 && a.charAt(i) != '\n') {
                    if (!map.containsKey(a.substring(i, i + 1))) {
                        sum ++;
                    }
                    map.put(a.substring(i, i + 1), 1);
                }
            }
            System.out.println(sum);
        }
    }
}