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#include <stdio.h>
#include <vector>
#include <map>
#include <unordered_set>
#include <queue>
#include <set>
#include <unordered_map>
#include <math.h>
#include <limits.h>
#include <algorithm>
#include <functional>
#include <iterator>
#include <algorithm>
#include <string>
#include <iostream>

using namespace std;

#define pb push_back
#define mp make_pair

typedef long long ll;
typedef unsigned long long ull;

using namespace std;

const ll MAXV = 1000000000;
const ll MINV = -1000000000;

int n, x;
vector<ll> values;


int try_count(bool go_up) {
	ll v = values[0];
	int score = 0;

	for (int i=1; i<n; ++i) {
		// cout << "i= " << i << endl;
		// cout << go_up << " v= " << v << " val= " << values[i] << endl;
		if (go_up) {
			if (v < values[i]) {
				v = values[i];
			} else {
				// cout << "d1" << endl;
				v = MAXV;
				score++;
			}
		} else {
			if (values[i] < v) {
				v = values[i];
			} else {
				// cout << "d2" << endl;		/
				v = MINV;
				score++;
			}
		}
		
		go_up = !go_up;
	}
	return score;
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);


	cin >> n;

	for (int i=0; i<n; ++i) {
		cin >> x;
		values.push_back(x);
	}

	int score_up = try_count(true);
	int score_down = try_count(false);

	// cout << score_up << endl;
	// cout << score_down << endl;

	cout << min(score_up, score_down) << endl;

	return 0;
}