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

bccdb
 z
 dfdeed
 aab
 y
 abac

a = sorted(input())
b = sorted(input(), reverse=True)
n = len(a)
a = ''.join(a[:(n+1)//2])
b = ''.join(b[:n//2])
name = [''] * (len(a) + len(b))
ia, ib, ic = 0, 0, 0
ja, jb, jc = len(a)-1, len(b)-1, len(name)-1
turn = 1
while ic <= jc:
    if turn == 1:
        if ib > jb: 
            name[ic] = a[ia]
            ic += 1
        elif a[ia] < b[ib]: 
            name[ic] = a[ia]
            ia += 1
            ic += 1
        else: 
            name[jc] = a[ja]
            ja-= 1
            jc-= 1
    else:
        if ia > ja: 
            name[ic] = b[ib]
            ic += 1
        elif b[ib] > a[ia]: 
            name[ic] = b[ib]
            ib += 1
            ic += 1
        else: 
            name[jc] = b[jb]
            jb -= 1
            jc -= 1
    turn = 1 - turn
print(''.join(name))
