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

bccdb
 z
 dfdeed
 aab
 y
 abac

def lowPriority():
    ret=sp1[0]
    for i in sp1:
        if(i<ret):
            ret=i
    del sp1[sp1.index(ret)]
    return ret
def highPriority():
    ret=sp2[0]
    for i in sp2:
        if(i>ret):
            ret=i
    del sp2[sp2.index(ret)]
    return ret
val1=raw_input()
val2=raw_input()
strin=""
sp1=[]
sp2=[]
for i in range(len(val1)):
    sp1.append(val1[i])
    sp2.append(val2[i])
i=0
while i < len(val1):
    if(i%2==0):
        strin=strin+lowPriority()
    else:
        strin=strin+highPriority()
    i+=1
print strin
    
    
