Given is an integer sequence A_1, ..., A_N of length N.

We will choose exactly \left\lfloor \frac{N}{2} \right\rfloor elements from this sequence so that no two adjacent elements are chosen.

Find the maximum possible sum of the chosen elements.

Here \lfloor x \rfloor denotes the greatest integer not greater than x.

Constraints

* 2 \leq N \leq 2\times 10^5
* |A_i|\leq 10^9
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
A_1 ... A_N


Output

Print the maximum possible sum of the chosen elements.

Examples

Input

6
1 2 3 4 5 6


Output

12


Input

5
-1000 -100 -10 0 10


Output

0


Input

10
1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000 1000000000


Output

5000000000


Input

27
18 -28 18 28 -45 90 -45 23 -53 60 28 -74 -71 35 -26 -62 49 -77 57 24 -70 -93 69 -99 59 57 -49


Output

295
n = int(input())
a = list(map(int, input().split()))
iseven=(n%2==0)

if n==2:
    print(max(a))
    exit()
dp = [[-float("inf") for _ in range(3)] for _ in range(n)]
dp[0][0]=a[0]
dp[1][1]=a[1]
if n>2:
    dp[2][2]=a[2]

for i in range(n):
    for k in range(3):
        if i+2<n:
            dp[i+2][k] = max(dp[i+2][k], dp[i][k] + a[i+2])
        if k<=1 and i+3<n:
            dp[i+3][k+1] = max(dp[i+3][k+1], dp[i][k] + a[i+3])
        if not iseven and k==0 and i+4<n:
            dp[i+4][k+2] = max(dp[i+4][k+2], dp[i][k] + a[i+4])


if iseven:
    ans=max([dp[-1][0],dp[-1][1]])
else:
    ans=max([dp[-3][0],dp[-2][1],dp[-1][2]])
print(ans)