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

bccdb
 z
 dfdeed
 aab
 y
 abac

o= raw_input()
i= raw_input()
o= sorted(list(o))
i= sorted(list(i))[::-1]
x= ['?']*len(o)
j= 0
while(j<len(x)):
	if(j%2==0):
		x[j]= o[j/2]
	else:
		x[j]= i[(j-1)/2] 
	j+= 1
print "".join(x)
