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

bccdb
 z
 dfdeed
 aab
 y
 abac

data1 = [el for el in input()]
data2 = [el for el in input()]
data1 = sorted(data1)
data2 = sorted(data2)
nazvan = ''
if len(data1) & 1:
    for i in range(len(data1) // 2):
        if data1[i] < data2[-i - 1]:
            nazvan += data1[i] + data2[-i - 1]
        else:
            nazvan += data2[-i - 1] + data1[i]           
    nazvan += data1[len(data2) // 2]
else:
    for i in range(len(data1) // 2):
        nazvan += data1[i] + data2[-i - 1]
print(nazvan)