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

bccdb
 z
 dfdeed
 aab
 y
 abac

A = list(input())
B = list(input())

A = sorted(A)
B = sorted(B)[::-1]


n = len(A)

for i in range(n):
	if i % 2:
		print(B[i//2], end="")
	else:
		print(A[i//2], end="")

print("")