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#include <bits/stdc++.h>

#define ll long long
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define boost ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define watch(x) cout << (#x) << " : " << x << '\n'

using namespace std;

const int INF = 1e9 + 128;

void solve() {
	int n;
	cin >> n;
	vector <int> a(n);
	for (auto& x : a)
        cin >> x;
    vector <int> cp = a;
    int ans = n, cur = 0;
    bool smaller = true;
    for (int i = 1; i < n; i++) {
        cur++;
        if (smaller && a[i] >= a[i-1]) a[i] = -INF;
            else if (!smaller && a[i] <= a[i-1]) a[i] = INF;
                else cur--;
        smaller = !smaller;
    }
    ans = min(ans, cur);
    a = cp;
    cur = 0;
    smaller = false;
    for (int i = 1; i < n; i++) {
        cur++;
        if (smaller && a[i] >= a[i-1]) a[i] = -INF;
            else if (!smaller && a[i] <= a[i-1]) a[i] = INF;
                else cur--;
        smaller = !smaller;
    }
    ans = min(ans, cur);
    cout << ans << '\n';
}

int main() {
	boost;
	solve();
	return 0;
}