import java.io.*;
public class problem4 {
	public static void main(String args []) throws IOException{		
		Writer output = null;
		String newLine = ""+'\r'+'\n';
		
		File fileout = new File("OUT4.txt");
		output = new BufferedWriter(new FileWriter(fileout));
		
		String text = null;
		BufferedReader reader = null;
		File file = new File ("DATA4.txt");
		reader = new BufferedReader(new FileReader(file)); 
		String[] lines = new String[5];
		int lot = 0; //lengthOfText
		int x = 0;//first coutner
		int y = 0;//second counter
		char go = ' ';//switch
		char goa = ' ';//ss
		while ( (text = reader.readLine()) != null){
			lot = text.length();
			go = 'y';
			for (x = 0; (x < lot) && ((go == 'y')); x++){//check||(go == 'n')
			goa = 'y';
			//System.out.println ("f"+x+" "+y);
				for (y = x + 1; (y < lot)&&(goa == 'y'); y++){
					if ((text.substring (x, x + 1).equals(text.substring(y, y + 1)))){
						go = 'y';
						goa = 'n';
					}
					else {
						go = 'n';
					}
					//System.out.println ("n"+x+" "+y+go);
				}//second for
				//System.out.println ("l"+x+" "+y);
			if ((go == 'n')){
					output.write (text.substring (x,x+1) + newLine);
			}
			}//firstfor
		}//while loop
		
		output.close();
		reader.close();
	}
	
}