import java.util.HashSet;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
String str = scanner.nextLine();
scanner.close();
HashSet<Character> hs = new HashSet<>();//不包含重复元素的集合
//write your code here......
for(int i=0;i<str.length();i++)
{
hs.add(str.charAt(i));
}
for (char c:hs) {
System.out.print(c);
}
}
}

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