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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(input())
b = sorted(input(), reverse=True)
res = []
i = 0
j = 0
while len(res) != len(a):
    res.append(a[i])
    i+= 1
    if len(res) == len(a):
        break
    res.append(b[j])
    j+= 1
print(''.join(res))