## https://yukicoder.me/problems/no/1392 MOD = 998244353 # ソースコードの出典URL: https://github.com/LyricalMaestro/at_coder_snippets/blob/af67863a2fe7f16cce8325bbc531f89968bfa525/src/conbination.py class CombinationCalculator: """ modを考慮したPermutation, Combinationを計算するためのクラス """ def __init__(self, size, mod): self.mod = mod self.factorial = [0] * (size + 1) self.factorial[0] = 1 for i in range(1, size + 1): self.factorial[i] = (i * self.factorial[i - 1]) % self.mod self.inv_factorial = [0] * (size + 1) self.inv_factorial[size] = pow(self.factorial[size], self.mod - 2, self.mod) for i in reversed(range(size)): self.inv_factorial[i] = ((i + 1) * self.inv_factorial[i + 1]) % self.mod def calc_combination(self, n, r): if n < 0 or n < r or r < 0: return 0 if r == 0 or n == r: return 1 ans = self.inv_factorial[n - r] * self.inv_factorial[r] ans %= self.mod ans *= self.factorial[n] ans %= self.mod return ans def calc_permutation(self, n, r): if n < 0 or n < r: return 0 ans = self.inv_factorial[n - r] ans *= self.factorial[n] ans %= self.mod return ans def main(): N, M = map(int, input().split()) P = list(map(int, input().split())) if M == 1: print(0) return cycles_id = 0 passed = [-1] * N for s_i in range(N): if passed[s_i] == -1: passed[s_i] = cycles_id p = P[s_i] - 1 while p != s_i: passed[p] = cycles_id p = P[p] - 1 cycles_id += 1 cycles = [0] * cycles_id for i in range(N): cycles[passed[i]] += 1 combi = CombinationCalculator(N + M, MOD) answer = 0 for m in reversed(range(2, M + 1)): ans = 1 for c in cycles: dp = [1, 0] for _ in range(1, c): new_dp = [0, 0] new_dp[1] += (dp[0] * (m - 1)) % MOD new_dp[1] %= MOD new_dp[0] += dp[1] new_dp[0] %= MOD new_dp[1] += (dp[1] * (m - 2)) % MOD new_dp[1] %= MOD dp = new_dp a = dp[1] a *= m a %= MOD ans *= a ans %= MOD ans2 = (ans * combi.calc_combination(M, m)) % MOD ans2 *= pow(-1, M - m, MOD) ans2 %= MOD answer += ans2 answer %= MOD answer *= combi.inv_factorial[M] answer %= MOD print(answer) if __name__ == "__main__": main()