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#include<bits/stdc++.h>

//TODO: przetestować to zadanie, żeby nie stracić punktów na trywie

using namespace std;

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n; cin>>n;
	vector<int> v(n);
	for(int i= 0; i < n; i++)cin>>v[i];
	int res = 1e9;
	for(int cas = 0; cas < 2; cas++){
		vector<array<int, 2>> dp(n);
		dp[0][0] = 0;
		dp[0][1] = 1;
		for(int i = 1; i < n; i++){
			if(i % 2 == cas){//ma byc gorka
				if(v[i] > v[i-1]){
					dp[i][0] = min(dp[i-1][0], dp[i-1][1]);
					dp[i][1] = dp[i][0] + 1;
				}else{
					dp[i][0] = dp[i-1][1];
					dp[i][1] = min(dp[i-1][0], dp[i-1][1]) + 1;
				}
			}else{//ma byc dolek
				if(v[i] < v[i-1]){
					dp[i][0] = min(dp[i-1][0], dp[i-1][1]);
					dp[i][1] = dp[i][0] + 1;
				}else{
					dp[i][0] = dp[i-1][1];
					dp[i][1] = min(dp[i-1][0], dp[i-1][1]) + 1;
				}
			}
		}
		//for(int i= 0; i < n; i++)cout<<dp[i][0]<<" ";
		//cout<<"\n";
		//for(int i = 0; i < n; i++)cout<<dp[i][1]<<" ";
		//cout<<"\n";
		res = min(res, min(dp[n-1][0], dp[n-1][1]));
		//cout<<"Koniec case\n\n";
	}
	cout<<res<<"\n";
}