def fiboA(N):
if N == 1 or N == 2:
return 1
return fiboA(N - 1) + fiboA(N - 2)
def fiboB(N):
if N == 1 or N == 2:
return 1
last2, last1 = 1, 1
for i in range(2,N):
nowVal = last1 + last2
last2, last1 = last1, nowVal
return nowVal