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

bccdb
 z
 dfdeed
 aab
 y
 abac

one = list(input())
two = list(input())
one.sort()
two.sort(reverse =True)

fin = []
leng = len(one)
fi = 0
se = 0
for i in range(leng):
    if(i%2==0):
        
        fin.append(one[fi])
        fi+=1
    else:
        fin.append(two[se])
        se+=1
print(''.join(fin))
    