bcdef
abbbc
 z
y
 reddit
abcdef
 abc
aaa
 y
z
 cbxz
aaaa

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            char o[] = in.next().toCharArray();
            char u[] = in.next().toCharArray();
            int n = o.length;
            Arrays.sort(o);
            Arrays.sort(u);
            char ans[] = new char[n];
            String oleg = "", igor = "";
            for (int i = 0; i < (n + 1) / 2; ++i) oleg += o[i];
            for (int i = n - 1; i >= n / 2; --i) igor += u[i];
            char ol[] = oleg.toCharArray();
            char il[] = igor.toCharArray();
            int oi = 0, oLast = ol.length - 1;
            int last = n - 1, cur = 0;
            int iLast = il.length - 1, ii = 0;
            for (int i = 0; i < n; ++i) {
                if (i % 2 == 0) {
                    if (ol[oi] < il[iLast]) {
                        ans[cur++] = ol[oi++];
                    } else {
                        ans[last--] = ol[oLast--];
                    }
                } else {
                    if (oLast >= 0 && il[ii] > ol[oLast]) {
                        ans[cur++] = il[ii++];
                    } else {
                        ans[last--] = il[iLast--];
                    }
                }
            }
            for (char x : ans) out.print(x);
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

    }
}

