A freight dispatcher has a manifest listing n cargo pallets in a single row; each pallet carries a declared value (a positive value represents profit, a negative value represents a handling penalty for damaged goods). Before loading the truck the dispatcher may permanently delete any number of pallets from the row -- each deletion removes exactly one pallet and the remaining pallets slide together into an unbroken row. Once finished deleting, the dispatcher must load one contiguous stretch of whatever row remains (possibly the whole remaining row, or nothing at all), subject to a single rule: no two pallets loaded onto the truck may carry the same declared value. Determine the greatest total declared value the dispatcher can load onto the truck.

Input format

The first line contains an integer n. The second line contains n space-separated integers, the declared values of the pallets in their original left-to-right order.

Output format

Print a single integer: the maximum total declared value that can be loaded onto the truck (0 if loading nothing is the best option).

Constraints

• 1 <= n <= 100000
• -10000 <= declared value <= 10000 for every pallet.

5
1 2 3 4 5

15

5
3 -1 3 -1 4

7