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

bccdb
 z
 dfdeed
 aab
 y
 abac

from sys import stdin, stdout

int_in = lambda: int(stdin.readline())
arr_in = lambda: [int(x) for x in stdin.readline().split()]
mat_in = lambda rows: [arr_in() for y in range(rows)]
str_in = lambda: stdin.readline().strip()
out = lambda o: stdout.write("{}\n".format(o))
arr_out = lambda o: out(" ".join(map(str, o)))
bool_out = lambda o: out("YES" if o else "NO")
tests = lambda: range(1, int_in() + 1)
case_out = lambda i, o: out("Case #{}: {}".format(i, o))


def solve(s, t):
    s.sort()
    t.sort(reverse=True)
    result = ""
    i = 0
    while len(result) < len(s):
        result += s[i] + t[i]
        i += 1
    return result[:len(s)]


if __name__ == "__main__":
    s = list(str_in())
    t = list(str_in())
    out(solve(s, t))