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

bccdb
 z
 dfdeed
 aab
 y
 abac

import java.io.IOException;
import java.io.InputStream;
import java.util.InputMismatchException;
import java.util.Arrays;

public class companyName {
	static class InputReader 
	{
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
 
        public InputReader(InputStream stream) {
            this.stream = stream;
        }
 
        public static boolean isWhitespace(int c) {
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
 
        public int read() {
            if (numChars == -1) {
                throw new InputMismatchException();
            }
            if (curChar >= numChars) {
                curChar = 0;
                try {
                        numChars = stream.read(buf);
                } catch (IOException e) {
                        throw new InputMismatchException();
                }
                if (numChars <= 0) {
                        return -1;
                }
            }
            return buf[curChar++];
        }
 
        public boolean isSpaceChar(int c) {
            if (filter != null) {
                return filter.isSpaceChar(c);
            }
            return isWhitespace(c);
        }
 
        public interface SpaceCharFilter {
 
            public boolean isSpaceChar(int ch);
        }
 
        public String next() {
            return nextString();
        }
        
        public char nextChar(){
        	int c=read();
        	while (isSpaceChar(c)) {
                c = read();
            }
        	return (char)c;
        }
 
        public String nextString() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            } while (!isSpaceChar(c));
            return res.toString();
        }
 
        public int nextInt() {
            int c = read();
            while (isSpaceChar(c)) {
                c = read();
            }
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9') {
                    throw new InputMismatchException();
                }
                res *= 10;
                res += c - '0';
                c = read();
            } while (!isSpaceChar(c));
            return res * sgn;
        }
 
        public Long nextLong() {
            return Long.parseLong(nextString());
        }
 
        public Double nextDouble() {
            return Double.parseDouble(nextString());
        }
    }
	
	public static void main(String[] args) {
		
		InputReader s=new InputReader(System.in);
		String str1=s.nextString(); 
		String str2=s.nextString();
		char[] oleg=str1.toCharArray();
		char[] igor=str2.toCharArray();
		
		Arrays.sort(igor);
		Arrays.sort(oleg);
		int n1=str1.length();
		int n2=(n1+1)/2;
		int olegS=0,olegE=n2-1;
		int igorS=n2,igorE=n1-1;
		
		char[] ans=new char[n1];
		int ansS=0,ansE=ans.length-1;
		
		
		for(int i=0;i<n1;i++)
		{
			if(i%2==0)
			{
				if(oleg[olegS]<igor[igorE])
					ans[ansS++]=oleg[olegS++];
				else
					ans[ansE--]=oleg[olegE--];
			}
			else
			{
				if(igor[igorE]>oleg[olegS])
					ans[ansS++]=igor[igorE--];
				else
					ans[ansE--]=igor[igorS++];
			}
		}
		System.out.println(ans);
	}

	

}