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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = list(x for x in input())
b = list(x for x in input())
sorted_a = sorted(a)
sorted_b = sorted(b, reverse=True)
for i in range(len(a)):
    if i % 2 == 0:
        print(sorted_a[i//2], end='')
    else:
        print(sorted_b[i//2], end='')
