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#include <algorithm>
#include <cstdint>
#include <ios>
#include <iostream>
#include <iterator>
#include <limits>
#include <string>
#include <vector>

template <typename T> void print_value(const T &v);

template <typename T> void debug(const T &v, const std::string &s) {
  std::cerr << s << ": '";
  print_value(v);
  std::cerr << "'\n";
}

template <> void print_value(const std::vector<int32_t> &v) {
  for (const auto x : v) {
    std::cerr << x << " ";
  }
}

template <typename T> void print_value(const T &v) { std::cerr << v; }

void prelude() {
  std::ios_base::sync_with_stdio(false);
  std::cin.tie(NULL);
}

int main() {
  prelude();
  int n;
  std::cin >> n;
  std::vector<int> chirps(n);
  for (int i = 0; i < n; ++i) {
    std::cin >> chirps[i];
  }

  // The optimal layout is either /\/\/\/\ or \/\/\/\/, we check both.
  // In any misaligned 
  const int dirs[] = {-1, 1};
  int best = std::numeric_limits<int>::max();
  for (int dir : dirs) {
    int needed_changes = 0;
    for (int i = 1; i < n; ++i) {
      int diff = chirps[i] - chirps[i - 1];
      if (diff * dir <= 0) {
        needed_changes += 1;
        // No change needed on the next step, and we need to skip either way
        // because we don't update the structure.
        ++i;
        dir *= -1;
      }
      dir *= -1;
    }
      best = std::min(needed_changes, best);
  }
  std::cout << best;
}