[Algorithm] [DP] 바텀업 예시

n = int(input())

arr = list(map(int, input().split()))

d = [0] * 100

# 3 1 1 5
# 3 3
d[0] = arr[0]
d[1] = max(arr[0], arr[1])
for i in range(2, n):
    d[i] = max(d[i - 1], d[i - 2] + arr[i])

print(d[n - 1])