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#include <iostream>
#include <vector>

using namespace std;

int test(vector<int> &v, bool increasing) {
  int changes = 0;
  for (int i = 1; i < v.size(); i++) {
    bool should_change = false;
    if (increasing && v[i] <= v[i - 1]) {
      should_change = true; 
    } 
    if (!increasing && v[i] >= v[i - 1]) {
      should_change = true;
    }
    if (should_change) {
      changes++;
      i++;
    } else {
      increasing = !increasing;
    }
  }
  return changes;
}

int main() {
  ios_base::sync_with_stdio(0);

  int n;
  cin >> n;
  vector<int> v;
  for (int i = 0; i < n; i++) {
    int a;
    cin >> a;
    v.push_back(a);
  }

  int increasing = test(v, true);
  int decreasing = test(v, false);
  if  (increasing < decreasing) {
    cout << increasing << endl;
  } else {
    cout << decreasing << endl;
  }

  return 0;
}