Recently, Tan started learning about trees, especially Explanation

In a given array Consider $A=1,B=2,$ and $C=3.$

Compute the sum of $B$ and $C$:$2+3=5.$ Compute

half of this sum: $\frac{5}{2}=2\mathrm{.}5.($not valid$)$

Compute the sum of A and $C$:$1+3=4.$ Compute

half of this sum: $\frac{4}{2}=2($valid$)$ Sample Output

$1$

Explanation

In a given array Consider $A=1,B=2,$ and $C=3.$

Compute the sum $B$ and $C$:$2+3=5.$ Compute

half of this sum: $\frac{5}{2}=2*5.($not valid$)$

Compute the sum of A and $C$:$1+3=4.$ Compute

half of this sum: $\frac{4}{2}=2($valid$)$

valid because $2$ is present as a remaining element.

Compute the sum of A and $B$:$2+1=3.$ Compute

half of this sum: $\frac{3}{2}=1\mathrm{.}5($not valid$).$

So the output will be $1.$

Binary Trees. He started thinking of creating a binary

tree that has precisely three nodes. One will be the

root node, and the other will be its child nodes. But the

condition is that the root node's value be equal to half

of the sum of the value of its child nodes.

He asked Taru to give him $n$ integers to create this kind

of binary tree. Seeing all those integers, Tan got

overwhelmed, so he needs your help finding any three

integers that can be created as a tree. Since many

possible combinations exist, you must tell the number

of triplets that can form the above binary tree.

Input Format

The first line will contain an integer $n.$

The next $n$ line will contain an integer each.

Constraints

$1n{10}^5$

$-{10}^3$ array element $s{10}^3$

Output Format