#pragma GCC target("avx2")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
bool is_kadomatsu(int a, int b, int c){
  return (b < a && b < c || b > a && b > c) && a != c;
}
template <typename T>
struct binary_indexed_tree{
	int N;
	vector<T> BIT;
	binary_indexed_tree(int n){
		N = 1;
		while (N < n){
			N *= 2;
		}
		BIT = vector<T>(N + 1, 0);
	}
	void add(int i, T x){
		i++;
		while (i <= N){
			BIT[i] += x;
			i += i & -i;
		}
	}
	T sum(int i){
		T ans = 0;
		while (i > 0){
			ans += BIT[i];
			i -= i & -i;
		}
		return ans;
	}
	T sum(int L, int R){
		return sum(R) - sum(L);
	}
};
int main(){
  int N;
  cin >> N;
  vector<int> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
    A[i]--;
  }
  if (A[1] < A[0]){
    for (int i = 0; i < N; i++){
      A[i] = N - 1 - A[i];
    }
  }
  long long ans = 0;
  for (int i = 0; i < N; i++){
    for (int j = i + 1; j < min(i + 5, N); j++){
      swap(A[i], A[j]);
      bool ok = true;
      for (int k = i - 2; k <= j; k++){
        if (0 <= k && k < N - 2){
          if (!is_kadomatsu(A[k], A[k + 1], A[k + 2])){
            ok = false;
          }
        }
      }
      if (ok){
        ans++;
      }
      swap(A[i], A[j]);
    }
  }
  vector<int> L(N, -1), R(N, N);
  for (int i = 0; i < N - 2; i++){
    if (i % 2 == 0){
      R[i] = min(R[i], A[i + 1]);
      R[i + 2] = min(R[i + 2], A[i + 1]);
      L[i + 1] = max(L[i + 1], max(A[i], A[i + 2]));
    } else {
      L[i] = max(L[i], A[i + 1]);
      L[i + 2] = max(L[i + 2], A[i + 1]);
      R[i + 1] = min(R[i + 1], min(A[i], A[i + 2]));
    }
  }
  vector<int> even(N, -1);
  for (int i = 0; i < N; i++){
    if (i % 2 == 0){
      even[A[i]] = i;
    }
  }
  binary_indexed_tree<int> BIT1(N);
  for (int i = 0; i < N; i++){
    if (even[i] != -1){
      ans += BIT1.sum(i + 1, N);
      BIT1.add(R[even[i]], 1);
    }
  }
  vector<int> odd(N, -1);
  for (int i = 0; i < N; i++){
    if (i % 2 == 1){
      odd[A[i]] = i;
    }
  }
  binary_indexed_tree<int> BIT2(N);
  for (int i = N - 1; i >= 0; i--){
    if (odd[i] != -1){
      ans += BIT2.sum(0, i);
      BIT2.add(L[odd[i]], 1);
    }
  }
  for (int i = 0; i < N; i++){
    for (int j = i + 5; j < N; j += 2){
      if (L[i] < A[j] && A[j] < R[i] && L[j] < A[i] && A[i] < R[j]){
        ans++;
      }
    }
  }
  for (int i = 0; i < N; i++){
    for (int j = i; j < min(i + 5, N); j++){
      if (L[i] < A[j] && A[j] < R[i] && L[j] < A[i] && A[i] < R[j]){
        ans--;
      }
    }
  }
  cout << ans << endl;
}