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.sort()
b.sort(reverse=True)
#print(a, b)
name = ''

for i in range(len(a)//2):
	name += a[i] 
	name += b[i]

if len(a)%2:
	name += a[len(a)//2]

print(name)
