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#include <bits/stdc++.h>
using namespace std;
using LL = long long;
#define e1 first
#define e2 second
#define pb push_back
#define OUT(x) {cout << x << "\n"; exit(0); }
#define TCOUT(x) {cout << x << "\n"; return; }
#define FOR(i, l, r) for(int i = (l); i <= (r); ++i)
#define rep(i, l, r) for(int i = (l); i < (r); ++i)
#define boost {ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); }
#define sz(x) int(x.size())
#define trav(a, x) for(auto& a : x)
#define all(x) begin(x), end(x)
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;

int main() {
	boost;
	int n; cin >> n;
	int res = INT_MAX;
	// always assume + - + - + -
	vi vec(n);
	rep(i, 0, n) cin >> vec[i];
	rep(step, 0, 2) {
		vi changed(n, INT_MAX), eq(n, INT_MAX);
		changed[0] = 1;
		eq[0] = 0;
		
		rep(i, 1, n) {
			// if this one is changed, it's always possible
			changed[i] = 1 + min(changed[i - 1], eq[i - 1]);
			bool should_be_smaller = i % 2;
			bool should_be_larger = !should_be_smaller;
			eq[i] = changed[i - 1]; //not changing always possible
			if (should_be_smaller && vec[i] < vec[i - 1]) {
				eq[i] = min(eq[i], eq[i - 1]);
			}
			if (should_be_larger && vec[i] > vec[i - 1]) {
				eq[i] = min(eq[i], eq[i - 1]);
			}
		}
		
		res = min(res, min(changed[n - 1], eq[n - 1]));
		rep(i, 0, n) vec[i] *= -1;
	}
	
	cout << res << "\n";
}