题解 | #兔子的数量#
兔子的数量
https://www.nowcoder.com/practice/8783056676de4396b0bf816a3561d62f
n=eval(input())
def cou(x):
if x==0:
return 0
elif x==1:
return 2
elif x==2:
return 3
else:
return cou(x-1)+cou(x-2)
print(cou(n))
