MOD = 998244353 MAX = 5000 fac = [1] * (MAX + 1) for i in range(MAX): fac[i + 1] = fac[i] * (i + 1) % MOD inv = [1] * (MAX + 1) inv[MAX] = pow(fac[MAX], MOD - 2, MOD) for i in range(MAX, 0, -1): inv[i - 1] = inv[i] * i % MOD n, m = map(int, input().split(' ')) p = [*map(int, input().split(' '))] assert 2 <= n <= 5000 assert 1 <= m <= n assert len(p) == n for i in range(n): assert 1 <= p[i] <= n p[i] -= 1 assert p[i] != i # 順列をサイクルに分解 cycle = [] used = [False] * n for i in range(n): if used[i]: continue l = 0 while not used[i]: used[i] = True l += 1 i = p[i] cycle.append(l) # 包除原理 a[i] := 1 ~ N を i 個の区別するグループに分ける分け方 整数が入っていないグループがあってもOK a = [1] * (m + 1) for i in range(2, m + 1): for l in cycle: a[i] *= pow(i-1, l, MOD) + (1 - i if l & 1 else i - 1) a[i] %= MOD ans = 0 for i in range(2, m + 1): ans += a[i] * fac[m] * inv[i] * inv[m - i] * (-1 if (m ^ i) & 1 else 1) ans *= inv[m] print(ans % MOD)