#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;
}
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]);
    } else {
      L[i] = max(L[i], A[i + 1]);
      L[i + 2] = max(L[i + 2], A[i + 1]);
    }
  }
  for (int i = 0; i < N; i++){
    for (int j = i + 5; j < N; j++){
      if (L[i] <= A[j] && A[j] <= R[i] && L[j] <= A[i] && A[i] <= R[j]){
        ans++;
      }
    }
  }
  cout << ans << endl;
}