Board Game

On another rainy day two friends are stuck indoors, so they invent a game.

On a sheet of paper they draw $n$ fields. Each field carries two numbers: its index (a distinct integer from $1$ to $n$) and its value (an integer between $-1000$ and $1000$). A pawn starts on field $1$. On every move the player rolls a six-sided die (its faces are numbered $1$ through $6$) and advances the pawn forward by the number rolled. The game ends the instant the pawn lands on field $n$. The player's score is the sum of the values of every field the pawn stood on, counting both the starting field $1$ and the final field $n$.

Because the players may pick any rolls they like, one game corresponds to a sequence of forward steps, each between $1$ and $6$ fields, that starts on field $1$ and stops exactly on field $n$. Compute the largest score achievable over all such sequences.

The first line contains an integer $n$ ($1 \le n \le 10^6$), the number of fields. The second line contains $n$ integers $w_1, w_2, \dots, w_n$ ($-1000 \le w_i \le 1000$), where $w_i$ is the value of field $i$.

Print one integer: the maximum score that can be obtained on the given board.