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

bccdb
 z
 dfdeed
 aab
 y
 abac

first = raw_input()
second = raw_input()

first = sorted([i for i in first])
second = sorted([i for i in second],reverse = True)

n = len(first)

ans = ['']*n
l = 0
r = n-1

toput = ''

for i in range(n/2):
    toput += first[i]
    toput += second[i]

if n % 2 != 0:
    toput += first[n/2]

#print toput

index = 0

while True:
    if index == n-1:
        ans[l] = toput[index]
        break

    if index % 2 == 0: # First player
        if toput[index] >= toput[index+1]:
            ans[r] = toput[index]
            r -= 1
        else:
            ans[l] = toput[index]
            l += 1
        


    else: # second
        if toput[index] <= toput[index+1]:
            ans[r] = toput[index]
            r -= 1
        else:
            ans[l] = toput[index]
            l += 1

        
    index += 1

    
print ''.join(ans)


