import java.io.*;
public class Main {
    public static class node {
        private int key;
        node left, right;
        node (int k) {
            key=k;
            left=right=null;
        }
    }

    static node root;
    static StreamTokenizer in;
    static PrintWriter out;

    public static void insert (int num, node r) {
        for (;;) {
            if (r.key==num) break;
            else if (r.key>num && r.left==null) {
                r.left = new node (num); break;
            } else if (r.key<num && r.right==null) {
                r.right = new node (num); break;
            }

            if (r.key>num) {
                r = r.left;
            } else r = r.right;
        }
    }

    public static void walkTree (node root) {
        if (root!=null) {
            walkTree (root.left);
            if ((root.left!=null && root.right==null) || (root.left==null && root.right!=null))
                    out.print (root.key+" ");
            walkTree (root.right);
        }
    }

    public static void main (String[] args) throws IOException {
        in = new StreamTokenizer (new BufferedReader(new InputStreamReader (System.in, "ISO-8859-1")));
        out = new PrintWriter (new OutputStreamWriter (System.out, "ISO-8859-1"));

        for (int i=0;;i++) {
            in.nextToken();
            if ((int)in.nval==0) break;

            if (i==0) {
                root = new node ((int)in.nval);
            }
            insert ((int)in.nval, root);
        }

        walkTree (root);

        out.close();
    }
}