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)
# print(a)
# print(b)
out = []
apos = 0
bpos = -1
for i in range(0,len(a),1):
    if(i % 2 == 0):
        out.append(a[apos])
        apos += 1
    else:
        out.append(b[bpos])
        bpos -= 1
print(''.join(out))
