Maximum Fruit from Three Consecutive Trees

You are given $n$ trees in a row, where each tree produces a certain amount of fruits. The fruits produced by the $i$-th tree is denoted by $a_i$ with $0 \leq a_i \leq 10^4$, and you have to find the maximum total amount of fruits that can be collected by selecting any three consecutive trees. Note that $n$ satisfies $3 \leq n \leq 10^5$. For example, if $n=5$ and the fruits array is [4, 2, 3, 7, 1], then the maximum sum is $4+2+3=12$. Read the input from standard input (stdin) and output the result to standard output (stdout).

inputFormat

The input consists of two lines. The first line contains an integer $n$, the number of trees. The second line contains $n$ space-separated integers representing the number of fruits produced by each tree.

outputFormat

Output a single integer which is the maximum total amount of fruits that can be collected from any three consecutive trees.## sample

5
4 2 3 7 1

12