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()))

dp = [[0] * 2 for i in range(N)]
dp[0][0] = 0
dp[0][1] = A[0]
dp[1][0] = 0
dp[1][1] = max(A[0:2])
for i in range(2, N-1):
    if i%2 == 0:
        dp[i][0] = max(dp[i-1][1], dp[i-2][0] + A[i])
        dp[i][1] = dp[i-2][1] + A[i]
    else:
        dp[i][0] = max(dp[i-1][0], dp[i-2][0] + A[i])
        dp[i][1] = max(dp[i-1][1], dp[i-2][1] + A[i])
#print(dp)

if N%2 == 0:
    ans = max(dp[N-2][1], dp[N-3][1] + A[N-1])
else:
    ans = max(dp[N-2][1], dp[N-3][0] + A[N-1])
print(ans)
