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

bccdb
 z
 dfdeed
 aab
 y
 abac

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

/**
 * Created by gamezovladislav on 25.03.2017.
 */

public class TaskC {

    public static void main(String[] args) throws IOException {
        InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        Solver solver = new Solver();
        solver.solve(in, out);
        out.close();
    }


    private static class Solver {
        public void solve(InputReader in, PrintWriter out) {
            String s = in.next();
            int cnt1[] = new int[30];
            int n = s.length();
            for (int i = 0; i < n; i++) {
                cnt1[s.charAt(i) - 'a']++;
            }
            s = in.next();
            int cnt2[] = new int[30];
            for (int i = 0; i < n; i++) {
                cnt2[s.charAt(i) - 'a']++;
            }
            int left1 = 0;
            int left2 = 0;
            int right1 = 25;
            int right2 = 25;
            int ansL = 0;
            int ansR = n - 1;
            int x1 = (n + 1) / 2;
            int x2 = n - x1;

            for (int i = 0; i < 26; i++) {
                if (cnt1[i] <= x1) {
                    x1 -= cnt1[i];
                } else {
                    cnt1[i] = x1;
                    x1 = 0;
                }
            }
            for (int i = 25; i >= 0; i--) {
                if (cnt2[i] <= x2) {
                    x2 -= cnt2[i];
                } else {
                    cnt2[i] = x2;
                    x2 = 0;
                }
            }

            while (left1 < 28 && cnt1[left1] == 0) left1++;
            while (left2 < 28 && cnt2[left2] == 0) left2++;

            while (right1 >= 0 && cnt1[right1] == 0) right1--;
            while (right2 >= 0 && cnt2[right2] == 0) right2--;

//            for (int i = 0; i < 26; i++) {
//                out.print(cnt1[i]);
//            }out.println();
//            for (int i = 0; i < 26; i++) {
//                out.print(cnt2[i]);
//            }
//
//            out.println(left1 + " " +right1);
//            out.println(left2 + " " +right2);
            char[] ans = new char[n];
            for (int i = 0; i < n; i++) {
                if (i % 2 == 0) {
                    ans[i] += c(left1);
                    cnt1[left1]--;
                    while (cnt1[left1] == 0 && left1 + 1 < 28) left1++;
                } else {
                    ans[i] = c(right2);
                    cnt2[right2]--;
                    while (cnt2[right2] == 0 && right2 > 0) right2--;
                }
            }
//            for (int i = 0; i < n; i++) {
//                if (i % 2 == 0) {
//                    if (left1 <= right2) {
//                        ans[ansL] = c(left1);
//                        ansL++;
//                        cnt1[left1]--;
//                        while (left1 < 26 && cnt1[left1] == 0) left1++;
//                    } else {
//                        ans[ansR] = c(right1);
//                        ansR--;
//                        cnt1[right1]--;
//                        while (right1 > 0 && cnt1[right1] == 0) right1--;
//                    }
//                } else {
//                    if (left1 <= right2) {
//                        ans[ansL] = c(right2);
//                        ansL++;
//                        cnt2[right2]--;
//                        while (right2 > 0 && cnt2[right2] == 0) right2--;
//                    } else {
//                        ans[ansR] = c(left2);
//                        ansR--;
//                        cnt2[left2]--;
//                        while (left2 < 26 && cnt2[left2] == 0) left2++;
//                    }
//                }
//            }
            for (int i = 0; i < n; i++) {
                out.print(ans[i]);
            }
        }

        private char c(int x) {
            return (char) (x + 'a');
        }
    }

    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();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
