Background

Special for beginners, ^_^

Form an Equilateral Triangle from Sticks

Problem Description

There are $n$ sticks. Now choose $4$ of them to form an equilateral triangle. In how many ways can this be done?

The answer should be taken modulo $10^9+7$.

Input Format

The first line contains one integer $n$.

The next $n$ lines each contain one integer; the $i$-th integer $a_i$ is the length of the $i$-th stick.

Output Format

One line containing one integer: the answer.

Sample Input

4
1
1
2
2

Sample Output

1

Constraints

1s, 1024KiB for each test case.

• For $30\%$ of the data, $n \le 5 \times 10^3$.
• For $100\%$ of the data, $1 \le n \le 10^5$ and $1 \le a_i \le 10^4$.