class FenwickTree: def __init__(self, size): self.n = size self.tree = [0] * (self.n + 2) # 下标从1到n def update(self, idx, delta): while idx <= self.n: self.tree[idx] += delta idx += idx & -idx def query(self, idx): res = 0 while idx > 0: res += self.tree[idx] idx -= idx & -idx return res def main(): import sys input = sys.stdin.read data = input().split() n = int(data[0]) p = list(map(int, data[1:n+1])) if n == 0: print(1) return # 初始化树状数组 ft = FenwickTree(n) for i in range(1, n+1): ft.update(i, 1) # 计算初始的(n-1)! 的值 current_fact = 1 for i in range(1, n): current_fact *= i sum_rank = 0 for i in range(n): # 当前元素是p[i] # 查询比p[i]小的可用的元素的数量 count = ft.query(p[i] - 1) sum_rank += count * current_fact # 移除当前元素 ft.update(p[i], -1) # 更新current_fact为 (n-i-2)! = current_fact // (n-i-1) if i < n-1: divisor = n - i - 1 current_fact = current_fact // divisor print(sum_rank + 1) if __name__ == "__main__": main()