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#include <bits/stdc++.h>
using namespace std;

const int N = 50005;

int n;
int tab[N];
int dp[2][N];	// 0 -> nie rob nic, 1 -> uwal

int solve() {
	dp[1][0] = 1;
	for (int i = 1; i < n; i++) {
		if (((tab[i] > tab[i - 1]) == (i & 1)) & (tab[i] != tab[i - 1])) {
			dp[0][i] = dp[0][i - 1];
		}
		else {
			dp[0][i] = N;
		}
		dp[0][i] = min(dp[0][i], dp[1][i - 1]);
		dp[1][i] = min(dp[0][i - 1], dp[1][i - 1]) + 1;
	}
	return min(dp[0][n - 1], dp[1][n - 1]);
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> tab[i];
	}
	int res = solve();
	for (int i = 0; i < n; i++) {
		tab[i] *= -1;
	}
	res = min(res, solve());
	cout << res << "\n";
}