#D2797. Count Pairs
Count Pairs
Count Pairs
You are given a prime number p, n integers a_1, a_2, …, a_n, and an integer k.
Find the number of pairs of indexes (i, j) (1 ≤ i < j ≤ n) for which (a_i + a_j)(a_i^2 + a_j^2) ≡ k mod p.
Input
The first line contains integers n, p, k (2 ≤ n ≤ 3 ⋅ 10^5, 2 ≤ p ≤ 10^9, 0 ≤ k ≤ p-1). p is guaranteed to be prime.
The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ p-1). It is guaranteed that all elements are different.
Output
Output a single integer — answer to the problem.
Examples
Input
3 3 0 0 1 2
Output
1
Input
6 7 2 1 2 3 4 5 6
Output
3
Note
In the first example:
(0+1)(0^2 + 1^2) = 1 ≡ 1 mod 3.
(0+2)(0^2 + 2^2) = 8 ≡ 2 mod 3.
(1+2)(1^2 + 2^2) = 15 ≡ 0 mod 3.
So only 1 pair satisfies the condition.
In the second example, there are 3 such pairs: (1, 5), (2, 3), (4, 6).
inputFormat
Input
The first line contains integers n, p, k (2 ≤ n ≤ 3 ⋅ 10^5, 2 ≤ p ≤ 10^9, 0 ≤ k ≤ p-1). p is guaranteed to be prime.
The second line contains n integers a_1, a_2, …, a_n (0 ≤ a_i ≤ p-1). It is guaranteed that all elements are different.
outputFormat
Output
Output a single integer — answer to the problem.
Examples
Input
3 3 0 0 1 2
Output
1
Input
6 7 2 1 2 3 4 5 6
Output
3
Note
In the first example:
(0+1)(0^2 + 1^2) = 1 ≡ 1 mod 3.
(0+2)(0^2 + 2^2) = 8 ≡ 2 mod 3.
(1+2)(1^2 + 2^2) = 15 ≡ 0 mod 3.
So only 1 pair satisfies the condition.
In the second example, there are 3 such pairs: (1, 5), (2, 3), (4, 6).
样例
6 7 2
1 2 3 4 5 6
3