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

bccdb
 z
 dfdeed
 aab
 y
 abac

s1 = [ch for ch in input()]
s2 = [ch for ch in input()]

s1.sort()
s2.sort()

n = len(s1)

ans = ""
for i in range(n):
    if (i % 2 == 0):
        ans += s1[i // 2]
    else:
        ans += s2[-(i // 2 + 1)]

print(ans)