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

bccdb
 z
 dfdeed
 aab
 y
 abac

import math
from collections import deque

def sort(arr):
    if len(arr) <= 1:
        return arr
    else:   
        pivot = arr[0]
        small, big, pivotlist = [], [], []
        for each in arr:
            if pivot < each:
                big.append(each)
            elif pivot > each:
                small.append(each)
            else:
                pivotlist.append(each)
        return sort(small) + pivotlist + sort(big)


smaller = map(list,raw_input().split())[0]
bigger = map(list,raw_input().split())[0]
length = len(smaller)
# print smaller, bigger
smaller = deque(sort(smaller))
bigger = deque(sort(bigger))
# print smaller, bigger
ans = ""
small_time, first = True, True
store_list = []
for i in range(length):
    if small_time:
        small_time = False
        if not first:
            if len(bigger) == 0 or bigger[-1] < smaller[0]:
                oleg = smaller.popleft()
                store_list.append(oleg)
            else:
                oleg = smaller.popleft()
                ans += oleg
        else:
            first = False
            if smaller[0] > bigger[-1]:
                oleg = smaller.popleft()
                store_list.append(oleg)
            else:
                oleg = smaller.popleft()
                ans += oleg
        # print "  current : ", ans, store_list
        # print "     ",smaller, bigger
    else:
        small_time = True
        if smaller[0] > bigger[-1]:
            igor_left_turn = (length / 2) - (i - 1) / 2
            if len(bigger) > igor_left_turn:
                while len(bigger) > igor_left_turn:
                    bigger.popleft()
                # print " bigger list trimmed : ", bigger, length, igor_left_turn
            igor = bigger.popleft()
            store_list.append(igor)
            
        else:
            igor = bigger.pop()
            ans += igor
        # print "  current : ", ans, store_list
        # print "     ",smaller, bigger
# print store_list
if len(store_list) > 0:
    for i in range(len(store_list) - 1,-1,-1):
        ans += store_list[i]
print ans
# print smaller, bigger

