Modified Ball Sampling

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Modular arithmetic, Linear Algebra, Hard, Fast Fourier transform, Number Theory, Mathematics
Problem

Some person is given a bag consisting of N distinct balls, represented by an array A of size N, where the ith ball has integer Ai written on it. Now, a game is played, where a player picks a ball from the bag K times, with repetition allowed.

He (the player) then notes the product of all numbers written on the balls picked, Soon, though he realizes that the number formed is too big, so he only considers the product Mod a given prime P. Let's call the product of the integers written on the picked balls Mod P as Z.

Considering that the probability of picking each ball is the same for each of the K picks, you need to find the Expected Value of Z. Let the answer be an irreducible fraction X/Y. You need to find and print XY1 Mod 998244353.

Input Format:

The first line consists of 3 space separated integers N ,P and K. The next line consists of N space separated integers , where the ith integer represents Ai

Output Format :

Print the expected value of Z.

Constraints :

1N100,000

3P50,000

1Ai<P

1K10,000,000

P is prime.

It can be proved, that for the following constraints Y1 Mod 998244353 always exists.

Time Limit: 7
Memory Limit: 256
Source Limit:
Explanation

Note that in the sample, for each pick among the K=2 ones, each number can be picked with probability equal to 1/2. The answer for the sample can be expressed as an irreducible fraction = 5/2 .

So, the answer is (521499122179) Mod 998244353

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