CF567C.Geometric Progression

普及/提高-

通过率:0%

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题目描述

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 kk and a sequence aa , consisting of nn integers.

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

A subsequence of length three is a combination of three such indexes i1,i2,i3i_{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.

A geometric progression with common ratio kk is a sequence of numbers of the form bk0,bk1,...,bkr1b·k^{0},b·k^{1},...,b·k^{r-1} .

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

输入格式

The first line of the input contains two integers, nn and kk ( 1<=n,k<=21051<=n,k<=2·10^{5} ), showing how many numbers Polycarp's sequence has and his favorite number.

The second line contains nn integers a1,a2,...,ana_{1},a_{2},...,a_{n} ( 109<=ai<=109-10^{9}<=a_{i}<=10^{9} ) — elements of the sequence.

输出格式

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 kk .

输入输出样例

  • 输入#1

    5 2
    1 1 2 2 4
    

    输出#1

    4
  • 输入#2

    3 1
    1 1 1
    

    输出#2

    1
  • 输入#3

    10 3
    1 2 6 2 3 6 9 18 3 9
    

    输出#3

    6

说明/提示

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.

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