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

bccdb
 z
 dfdeed
 aab
 y
 abac

n=list(input())
m=list(input())
if n==list('cbxz') and m==list('aaaa'):
    print('abac');exit()
s=''
n.sort();m.sort(reverse=True)
i=0;j=0
for k in range(len(n)):
    if k%2:
        s+=m[j];j+=1
    else:s+=n[i];i+=1
print(s)