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

bccdb
 z
 dfdeed
 aab
 y
 abac

oleg = sorted([str(x) for x in input()])
igor = sorted([str(x) for x in input()])
n = len(oleg)
o = 0
i = n-1
name = ''
for  j in range(n):
    if(j%2==0):
        name += oleg[o]
        o+=1
    else:
        name += igor[i]
        i-=1
print(name)