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

bccdb
 z
 dfdeed
 aab
 y
 abac

import math
def get_res(s, t):
    res = ''
    N = len(s)
    slist = sorted(s)
    tlist = sorted(t, reverse=True)
    sk = 0
    tk = 0
    flag = 0
    cnt = 0
    while cnt < N:
        if flag == 0:
            res += slist[sk]
            sk += 1
            flag = 1
        else:
            res += tlist[tk]
            tk += 1
            flag = 0
        cnt += 1

    return res

#N = int(raw_input())  

s = raw_input().split(" ")[0]
t = raw_input().split(" ")[0]
result = get_res(s, t)
print "{}".format(result)
