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

bccdb
 z
 dfdeed
 aab
 y
 abac

oleg = sorted(list(raw_input()))
igor = sorted(list(raw_input()))
igor.reverse()
q=len(oleg)
new_str = ['']*q

for i in xrange(q):
    if i%2 == 0:
        new_str[i] = oleg.pop(0)
    else:
        new_str[i] = igor.pop(0)

print ''.join(new_str)


