import java.io.*;
public class Q4 {
	public static void main(String[] args) throws IOException {
		BufferedReader in= new BufferedReader (new FileReader ("DATA4.txt"));
		PrintWriter out=new PrintWriter (new FileWriter ("OUT4.txt"));
		String data;
		int l;
		char temp;
		for (int count=0;count<5;count++){

			data=in.readLine();
			l=data.length();
				for (int i=0;i<l;i++){
					int a=0;
					temp=data.charAt(i);
					for (int m=0;m<l;m++){
						if (temp==data.charAt(m)) a++;
						}
				if (a==1) {
					out.println(temp);
					break;}
				}
			}
		out.close();
	}
}