#include <bits/stdc++.h>
using namespace std;
template <typename T, typename U>
inline void smin(T &a, const U &b) {
  if (a > b) a = b;
}
template <typename T, typename U>
inline void smax(T &a, const U &b) {
  if (a < b) a = b;
}
template <typename T>
inline void gn(T &first) {
  char c, sg = 0;
  while (c = getchar(), (c > '9' || c < '0') && c != '-')
    ;
  for ((c == '-' ? sg = 1, c = getchar() : 0), first = 0; c >= '0' && c <= '9';
       c = getchar())
    first = (first << 1) + (first << 3) + c - '0';
  if (sg) first = -first;
}
template <class T, class T1>
inline void gn(T &first, T1 &second) {
  gn(first);
  gn(second);
}
template <class T, class T1, class T2>
inline void gn(T &first, T1 &second, T2 &z) {
  gn(first);
  gn(second);
  gn(z);
}
template <typename T>
inline void print(T first) {
  if (first < 0) {
    putchar('-');
    return print(-first);
  }
  if (first < 10) {
    putchar('0' + first);
    return;
  }
  print(first / 10);
  putchar(first % 10 + '0');
}
template <typename T>
inline void println(T first) {
  print(first), putchar('\n');
}
template <typename T>
inline void printsp(T first) {
  print(first), putchar(' ');
}
template <class T, class T1>
inline void print(T first, T1 second) {
  printsp(first), println(second);
}
template <class T, class T1, class T2>
inline void print(T first, T1 second, T2 z) {
  printsp(first), printsp(second), println(z);
}
int power(int a, int b, int m, int ans = 1) {
  for (; b; b >>= 1, a = (long long)a * a % m)
    if (b & 1) ans = (long long)ans * a % m;
  return ans;
}
map<pair<int, int>, bool> mp;
int a[200000], t[200000], flag[200000], cnt, n;
vector<int> v;
bool can(int i) {
  if (i < 1 || i >= n) return true;
  if (i & 1)
    return a[i] < a[i + 1];
  else
    return a[i] > a[i + 1];
}
void go(int u, int v) {
  if (u > v) swap(u, v);
  swap(a[u], a[v]);
  for (int i = 0; i < cnt; i++)
    if (!can(t[i])) {
      swap(a[u], a[v]);
      return;
    }
  if (!can(u) || !can(u - 1) || !can(v) || !can(v - 1)) {
    swap(a[u], a[v]);
    return;
  }
  swap(a[u], a[v]);
  mp[pair<int, int>(u, v)] = 1;
}
int main() {
  gn(n);
  for (int i = 1; i <= n; i++) gn(a[i]);
  for (int i = 1; i < n; i++)
    if (!can(i)) {
      t[cnt++] = i;
    }
  if (cnt > 5) {
    puts("0");
    return 0;
  }
  for (int i = 0; i < cnt; i++) {
    flag[t[i]] = flag[t[i] + 1] = 1;
  }
  for (int i = 1; i <= n; i++)
    if (flag[i])
      for (int j = 1; j <= n; j++)
        if (i != j) go(i, j);
  printf("%d\n", mp.size());
  while (clock() < 1900) true;
  return 0;
}
