N = int(input()) # 1<=N<=90
d = [[0]*2 for _ in range(N+1)]
d[1] = [0,1]
for i in range(2,N+1):
for j in range(0,1+1): #j: 0 , 1
if j ==0:
d[i][j] = d[i-1][0] + d[i-1][1]
elif j ==1:
d[i][j] = d[i-1][0]
result = sum(d[N])
print(result)
모범답안
d = [0]*91
n = int(input())
d[1] = 1
d[2] = 1
for i in range(3, n+1):
d[i] = d[i-1] + d[i-2]
print(d[n])