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

bccdb
 z
 dfdeed
 aab
 y
 abac

t = sorted(list(input()), )
m = len(t)
il = sorted(list(input()), reverse=True)

ans = ''
for i in range(m):
    ans = ans + t[i]+ il[i]

c = 0
while c != m:
    print(ans[c], end ='')
    c += 1