One day, little Vasya found himself in a maze consisting of $(*n* + 1)$ rooms, numbered from $1$ to $(*n* + 1)$. Initially, Vasya is at the first room and to get out of the maze, he needs to get to the $(*n* + 1)$-th one.

The maze is organized as follows. Each room of the maze has two one-way portals. Let's consider room number $*i*$ $(1 ≤ *i* ≤ *n*)$, someone can use the first portal to move from it to room number $(*i* + 1)$, also someone can use the second portal to move from it to room number $*p*_{*i*}$, where $1 ≤ *p*_{*i*} ≤ *i*$.

In order not to get lost, Vasya decided to act as follows.

• Each time Vasya enters some room, he paints a cross on its ceiling. Initially, Vasya paints a cross at the ceiling of room $1$.
• Let's assume that Vasya is in room $*i*$ and has already painted a cross on its ceiling. Then, if the ceiling now contains an odd number of crosses, Vasya uses the second portal (it leads to room $*p*_{*i*}$), otherwise Vasya uses the first portal.

Help Vasya determine the number of times he needs to use portals to get to room $(*n* + 1)$ in the end.

Input

The first line contains integer $*n*$ ($1 ≤ *n* ≤ 10^{3}$) — the number of rooms. The second line contains $*n*$ integers $*p*_{*i*}$ ($1 ≤ *p*_{*i*} ≤ *i*$). Each $*p*_{*i*}$ denotes the number of the room, that someone can reach, if he will use the second portal in the $*i*$-th room.

Output

Print a single number — the number of portal moves the boy needs to go out of the maze. As the number can be rather large, print it modulo $1000000007$ $(10^{9} + 7)$.