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#include <bits/stdc++.h>

using namespace std;

const int N = 1e6 + 50;

int n, a[N], dp[N][2];

int solve() {
	memset(dp, 0x3f, sizeof dp);
	// dp[i][0/1]：目前到 i，a_i 是否被修改过
	dp[1][0] = 0, dp[1][1] = 1;
	for (int i = 2; i <= n; ++i) {
		if (i % 2 == 0) {
			// <=
			if (a[i - 1] < a[i])
				dp[i][0] = min(dp[i - 1][0], dp[i - 1][1]);
			else
				dp[i][0] = dp[i - 1][1];
			dp[i][1] = min(dp[i - 1][1], dp[i - 1][0]) + 1;
		}
		else {
			// >=
			if (a[i - 1] > a[i])
				dp[i][0] = min(dp[i - 1][0], dp[i - 1][1]);
			else
				dp[i][0] = dp[i - 1][1];
			dp[i][1] = min(dp[i - 1][1], dp[i - 1][0]) + 1;
		}
	}
	return min(dp[n][0], dp[n][1]);
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	cin >> n;
	for (int i = 1; i <= n; ++i)
		cin >> a[i];
	int ans = solve();
	for (int i = 1; i <= n; ++i)
		a[i] = -a[i];
	ans = min(ans, solve());
	cout << ans << '\n';
}