import java.io.*;
import java.util.*;
public class Main{
public static void main(String[] args) throws Exception{
Scanner sc = new Scanner(System.in);
while(sc.hasNextLine()){
String s = sc.nextLine();
char[] cc = s.toCharArray();
int[] count = new int[26];
for(char c : cc){
count[c - 'a'] += 1;
}
int minValue = Integer.MAX_VALUE;
for(int i = 0; i < 26; ++i){
if(count[i] != 0 && minValue > count[i]){
minValue = count[i];
}
}
Set<Character> set = new HashSet<>();
for(int i = 0; i < 26; ++i){
if(count[i] == minValue){
set.add((char)('a' + i));
}
}
for(char c : cc){
if(!set.contains(c)){
System.out.print(c);
}
}
System.out.println();
}
}
}