Codeforces Round #Pi (Div. 2)
C
Geometric Progression
Codeforces
1700
原题
← BD →
翻译中…

Polycarp loves geometric progressions very much. Since he was only three years old, he loves only the progressions of length three. He also has a favorite integer $*k*$ and a sequence $*a*$, consisting of $*n*$ integers.

翻译中…

He wants to know how many subsequences of length three can be selected from $*a*$, so that they form a geometric progression with common ratio $*k*$.

翻译中…

A subsequence of length three is a combination of three such indexes $*i*_{1}, *i*_{2}, *i*_{3}$, that $1 ≤ *i*_{1} < *i*_{2} < *i*_{3} ≤ *n*$. That is, a subsequence of length three are such groups of three elements that are not necessarily consecutive in the sequence, but their indexes are strictly increasing.

翻译中…

A geometric progression with common ratio $*k*$ is a sequence of numbers of the form $*b*·*k*^{0}, *b*·*k*^{1}, ..., *b*·*k*^{*r* - 1}$.

翻译中…

Polycarp is only three years old, so he can not calculate this number himself. Help him to do it.

翻译中…

Input

翻译中…

The first line of the input contains two integers, $*n*$ and $*k*$ ($1 ≤ *n*, *k* ≤ 2·10^{5}$), showing how many numbers Polycarp's sequence has and his favorite number.

翻译中…

The second line contains $*n*$ integers $*a*_{1}, *a*_{2}, ..., *a*_{*n*}$ ($- 10^{9} ≤ *a*_{*i*} ≤ 10^{9}$) — elements of the sequence.

翻译中…

Output

翻译中…

Output a single number — the number of ways to choose a subsequence of length three, such that it forms a geometric progression with a common ratio $*k*$.

翻译中…

Note

翻译中…

In the first sample test the answer is four, as any of the two 1s can be chosen as the first element, the second element can be any of the 2s, and the third element of the subsequence must be equal to 4.

翻译中…

样例

Input #1
5 2
1 1 2 2 4
Output #1
4
InputCopy OutputCopy
Input #2
3 1
1 1 1
Output #2
1
InputCopy OutputCopy
Input #3
10 3
1 2 6 2 3 6 9 18 3 9
Output #3
6
InputCopy OutputCopy
题目信息
题号
567C
时间限制
1 s
内存限制
256 MB
标签
二分
数据结构
动态规划

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