def zero(x):
t = ""
for a,b in zip(x[::2],x[1::2]):
t += b+a
return t
def one(x):
t = ""
for a,b in zip(x[::2],x[1::2]):
t += b+a if b<a else a+b
return t
def two(x):
t = ""
for a,b in zip(x[:len(x)//2],x[len(x)//2:]):
t += a+b
return t