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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = list(raw_input())
n = len(a)
a.sort()
b = list(raw_input())
b.sort()
c = ""
for i in xrange(n):
    if not (i & 1) :
        c += a[i >> 1]
        #print a[i >> 1]
    else :
        c += b[n - (i >> 1) - 1]
        #print b[n - (i >> 1) - 1]
print c