NumberEater

NumberEater is a famous monster from Byteland. It eats numbers, but it is very picky: every day its meal must be unique. The monster is given a sequence of integers $a_1, a_2, \ldots, a_n$. It chooses a start position $i$ and an end position $j$ ($1 \le i \le j \le n$) and prepares a meal made of the elements $a_i, a_{i+1}, \ldots, a_j$.

The monster considers two meals $[i_1, j_1]$ and $[i_2, j_2]$ to be identical when they contain the same set of numbers, that is:

$\{a_k : i_1 \le k \le j_1\} = \{a_k : i_2 \le k \le j_2\}$

Help NumberEater count how many different meals it can prepare using the sequence $a$.

The first line contains one integer $n$ ($1 \le n \le 500$), the length of the sequence $a$. Each of the next $n$ lines contains one element of the sequence. Every element is at least $1$ and at most $500$.

Print a single integer: the number of different meals that NumberEater can prepare.