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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(input())
b = sorted(input())
b.reverse()
ans = []
ia, ib = 0, 0
for i in range(int(len(a)/2)):
    ans.append(a[ia])
    ans.append(b[ib])
    ia += 1
    ib += 1
if len(a)%2 != 0:
    ans.append(a[ia])
for i in ans:
    print(i, end='')
print()
