## https://yukicoder.me/problems/no/2616 MOD = 998244353 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 class BinaryIndexTree: """ フェニック木(BinaryIndexTree)の基本的な機能を実装したクラス """ def __init__(self, size): self.size = size self.array = [0] * (size + 1) def add(self, x, a): index = x while index <= self.size: self.array[index] += a index += index & (-index) def sum(self, x): index = x ans = 0 while index > 0: ans += self.array[index] index -= index & (-index) return ans def least_upper_bound(self, value): if self.sum(self.size) < value: return -1 elif value <= 0: return 0 m = 1 while m < self.size: m *= 2 k = 0 k_sum = 0 while m > 0: k0 = k + m if k0 < self.size: if k_sum + self.array[k0] < value: k_sum += self.array[k0] k += m m //= 2 if k < self.size: return k + 1 else: return -1 def main(): N = int(input()) P = list(map(int, input().split())) combi = CombinationCalculator(2 * N, MOD) bit = BinaryIndexTree(N) forward_pm = [0 for _ in range(N)] for i in range(N): p = P[i] forward_pm[i] = bit.sum(p) bit.add(p, 1) answer = 0 for i in range(N): fm = forward_pm[i] bm = P[i] - 1 - fm fp = i - fm bp = N - P[i] - fp a = combi.calc_combination(fm + bp, fm) b = combi.calc_combination(fp + bm, fp) answer += (a * b) % MOD answer %= MOD print(answer) if __name__ == "__main__": main()