#include <bits/stdc++.h>
using namespace std;
int inf_int = 2e9;
long long inf_ll = 2e18;
const double pi = 3.1415926535898;
template <typename T, typename T1>
void prin(vector<pair<T, T1> >& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i].first << " " << a[i].second << "\n";
  }
}
template <typename T>
void prin(vector<T>& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i];
    if (i < a.size() - 1)
      cout << " ";
    else
      cout << "\n";
  }
}
template <typename T>
void prin(set<T>& a) {
  for (auto it = a.begin(); it != a.end(); it++) {
    cout << *it << " ";
  }
}
template <typename T>
void prin_new_line(vector<T>& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i] << "\n";
  }
}
template <typename T, typename T1>
void prin_new_line(vector<pair<T, T1> >& a) {
  for (int i = 0; i < a.size(); i++) {
    cout << a[i].first << " " << a[i].second << "\n";
  }
}
int sum_vec(vector<int>& a) {
  int s = 0;
  for (int i = 0; i < a.size(); i++) {
    s += a[i];
  }
  return s;
}
template <typename T>
T max(vector<T>& a) {
  T ans = a[0];
  for (int i = 1; i < a.size(); i++) {
    ans = max(ans, a[i]);
  }
  return ans;
}
template <typename T>
T min(vector<T>& a) {
  T ans = a[0];
  for (int i = 1; i < a.size(); i++) {
    ans = min(ans, a[i]);
  }
  return ans;
}
template <typename T>
T min(T a, T b, T c) {
  return min(a, min(b, c));
}
template <typename T>
T max(T a, T b, T c) {
  return max(a, max(b, c));
}
double s_triangle(double x1, double y1, double x2, double y2, double x3,
                  double y3) {
  return abs(((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) / 2);
}
bool overflow(long long a, long long b) {
  if (a * b / b != a) return true;
  return false;
}
bool debug = 0;
const int maxn = 1e5 + 7;
void solve() {
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  if (n % 2 == 0)
    a.push_back(0);
  else
    a.push_back(inf_int);
  vector<int> b;
  for (int i = 1; i < n; i = i + 2) {
    if (a[i] <= a[i - 1] || a[i] <= a[i + 1]) {
      b.push_back(i);
    }
  }
  vector<int> mojno_postavit(n);
  for (int i = 1; i < n; i = i + 2) {
    int x = max(a[i - 1], a[i + 1]) + 1;
    mojno_postavit[i] = x;
  }
  mojno_postavit[0] = a[1] - 1;
  for (int i = 2; i < n; i = i + 2) {
    mojno_postavit[i] = min(a[i - 1], a[i + 1]) - 1;
  }
  if (b.size() > 3) {
    cout << 0;
    return;
  } else if (b.size() == 1) {
    long long ans = 0;
    int x = b[0];
    x = max(a[x - 1], a[x + 1]) + 1;
    set<int> in;
    in.insert(b[0] - 1);
    in.insert(b[0]);
    in.insert(b[0] + 1);
    vector<int> c;
    for (auto it = in.begin(); it != in.end(); it++) {
      c.push_back(*it);
    }
    for (int i = 0; i < c.size(); i++) {
      for (int e = i + 1; e < c.size(); e++) {
        vector<int> x = a;
        swap(x[c[i]], x[c[e]]);
        bool k = 1;
        for (int f = 1; f < n; f = f + 2) {
          if (x[f] <= x[f - 1] || x[f] <= x[f + 1]) {
            k = 0;
            break;
          }
        }
        if (k) {
          ans++;
        }
      }
    }
    for (int i = 1; i < n; i = i + 2) {
      if (i < b[0] - 1 || i > b[0] + 1)
        if (a[i] >= x && mojno_postavit[i] <= a[b[0]]) {
          ans++;
        }
    }
    for (int i = 0; i < n; i = i + 2) {
      if (i < b[0] - 1 || i > b[0] + 1)
        if (a[i] >= x && mojno_postavit[i] >= a[b[0]]) {
          ans++;
        }
    }
    int ind = b[0];
    if (a[ind] > a[ind - 1] && a[ind] <= a[ind + 1]) {
      int c = a[ind] - 1;
      for (int i = 1; i < n; i = i + 2) {
        if (i < b[0] - 1 || i > b[0] + 1)
          if (i != ind && a[i] <= c && mojno_postavit[i] <= a[ind + 1]) {
            ans++;
          }
      }
      for (int i = 0; i < n; i = i + 2) {
        if (i < b[0] - 1 || i > b[0] + 1)
          if (a[i] <= c && mojno_postavit[i] >= a[ind + 1]) {
            ans++;
          }
      }
    }
    if (a[ind] > a[ind + 1] && a[ind] <= a[ind - 1]) {
      int c = a[ind] - 1;
      for (int i = 1; i < n; i = i + 2) {
        if (i < b[0] - 1 || i > b[0] + 1)
          if (i != ind && a[i] <= c && mojno_postavit[i] <= a[ind - 1]) {
            ans++;
          }
      }
      for (int i = 0; i < n; i = i + 2) {
        if (i < b[0] - 1 || i > b[0] + 1)
          if (a[i] <= c && mojno_postavit[i] >= a[ind - 1]) {
            ans++;
          }
      }
    }
    cout << ans;
  } else if (b.size() == 3) {
    set<int> in;
    in.insert(b[0] - 1);
    in.insert(b[0]);
    in.insert(b[0] + 1);
    in.insert(b[1] - 1);
    in.insert(b[1]);
    in.insert(b[1] + 1);
    in.insert(b[2] - 1);
    in.insert(b[2]);
    in.insert(b[2] + 1);
    vector<int> c;
    for (auto it = in.begin(); it != in.end(); it++) {
      c.push_back(*it);
    }
    int ans = 0;
    for (int i = 0; i < c.size(); i++) {
      for (int e = i + 1; e < c.size(); e++) {
        vector<int> x = a;
        swap(x[c[i]], x[c[e]]);
        bool k = 1;
        for (int f = 1; f < n; f = f + 2) {
          if (x[f] <= x[f - 1] || x[f] <= x[f + 1]) {
            k = 0;
            break;
          }
        }
        if (k) {
          ans++;
        }
      }
    }
    cout << ans;
  } else if (b.size() == 2) {
    int ans = 0;
    if (b[1] - b[0] == 2) {
      if (a[b[0]] > a[b[0] - 1] && a[b[1]] > a[b[1] + 1] &&
          a[b[0]] <= a[b[0] + 1] && a[b[1]] <= a[b[1] - 1]) {
        int x = min(a[b[0]], a[b[1]]) - 1;
        int val = a[b[0] + 1];
        for (int i = 1; i < n; i = i + 2) {
          if (i < b[0] - 1 || i > b[1] + 1) {
            if (a[i] <= x && mojno_postavit[i] <= val) {
              ans++;
            }
          }
        }
        for (int i = 0; i < n; i = i + 2) {
          if (i < b[0] - 1 || i > b[1] + 1) {
            if (a[i] <= x && mojno_postavit[i] >= val) {
              ans++;
            }
          }
        }
      }
    }
    set<int> in;
    in.insert(b[0] - 1);
    in.insert(b[0]);
    in.insert(b[0] + 1);
    in.insert(b[1] - 1);
    in.insert(b[1]);
    in.insert(b[1] + 1);
    vector<int> c;
    for (auto it = in.begin(); it != in.end(); it++) {
      c.push_back(*it);
    }
    for (int i = 0; i < c.size(); i++) {
      for (int e = i + 1; e < c.size(); e++) {
        vector<int> x = a;
        swap(x[c[i]], x[c[e]]);
        bool k = 1;
        for (int f = 1; f < n; f = f + 2) {
          if (x[f] <= x[f - 1] || x[f] <= x[f + 1]) {
            k = 0;
            break;
          }
        }
        if (k) {
          ans++;
        }
      }
    }
    cout << ans;
  }
}
int main() {
  if (!debug) {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
  }
  int t = 1;
  while (t--) solve();
  return 0;
}
