题解 | #字符集合#

import java.util.Scanner;
public class Main {
    public static String func(String s) {
        int ret = 0;
        char[] arr = new char[128];
        StringBuilder str = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            if (arr[s.charAt(i)] == 0) {
                str.append(s.charAt(i));
                arr[s.charAt(i)]++;
            }
        }
        return str.toString();
    }
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextLine()) {
            System.out.println(func(in.nextLine()));
        }
    }
}