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

if __name__ == "__main__":
    n = int(input())
    nums = [int(s) for s in input().split()]
    odds = [0]        
    for num in nums[::2]:
        odds.append(num + odds[-1])
    
    res = [0]
    for i, num in enumerate(nums[1::2]):
        res.append(max(res[-1]+num, odds[i+1]))
    
    if n % 2 == 0:
        print(res[-1])
    else:
        ans = float('-inf')
        for i, r in enumerate(res):
            ans = max(ans, res[i] + odds[-1] - odds[i+1])
        print(ans)

