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 = sort(bigger)
# print smaller, bigger
ans = ""
small_time = True
for i in range(length):
    if small_time:
        small_time = False
        letter = smaller.popleft()
    else:
        small_time = True
        letter = bigger.pop()
    ans += letter
print ans

