import java.util.*;
import java.io.*;

public class uniqueletter{
	public static void main (String[] args){
		File infile = new File("data4.txt");
		File outfile = new File("out4.txt");
		Scanner read;
		PrintStream ps;
		try{
			read = new Scanner(infile);
			ps = new PrintStream(new FileOutputStream(outfile));
			String word;
			Boolean found;
			for (int a=0; a<5;a++){
				found = false;
				word=read.nextLine();
				for (int b=0; b<word.length(); b++){
					if (!found && word.indexOf(word.charAt(b))==word.lastIndexOf(word.charAt(b))){
						ps.println(word.charAt(b));
						found=true;
					}
				}
			}
			ps.close();
			read.close();
		} catch (Exception e){
			System.err.print("This operation could not be completed.");
		}
	}
}