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

bccdb
 z
 dfdeed
 aab
 y
 abac

oleg = raw_input()
blah = raw_input()
s1 = sorted(oleg)
s2 = sorted(blah, reverse = True)
s = ""
count = 0
k = 0
for i in xrange(len(s1)):
	if(count%2==0):
		s+=s1[k]
	else:
		s+=s2[k]
		k+=1
	count+=1
print s