import java.util.*;
import java.lang.*;
 
 
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
        String str = "Hellllllllllo";
        System.out.println(Main.removeDuplicates(str));
	}
 
	public static String removeDuplicates(String str) {
        int checker = 0;
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < str.length(); ++i) {
            int val = str.charAt(i) - 'a';
            if ((checker & (1 << val)) == 0)
                buffer.append(str.charAt(i));
            checker |= (1 << val);
        }
        return buffer.toString();
    }
}

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