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

bccdb
 z
 dfdeed
 aab
 y
 abac

x=raw_input()
le=len(x)
a=0
b=le-1
y=raw_input()
x=sorted(x)
y=sorted(y)
e=""
for i in range(le):
    if i%2==0:
        e+=x[a]
        a+=1
    else:
        e+=y[b]
        b-=1
print e