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


#define st first
#define nd second
#define pb push_back
#define sz(x) (int)x.size()
#define all(x) x.begin(),x.end()
#define sor(x) sort(all(x))
#define rev(x) reverse(all(x))
#define rsz(x) resize(x)
#define BOOST ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);

typedef long long ll;
typedef pair<int,int>pii;
typedef long double ldl;
typedef pair<ll,ll>pll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vii;
typedef vector<pll>vll;
typedef unsigned long long ul;

const int mX_N = 50010;
const int INF = 1e5;
int dp[mX_N][3];//najpierw ostatnia, potem przedostatnia//0 - nie zmieniamy, 1-zmieniamy na dolny, 2 - zmienimy na gorne
int T[mX_N];

int main()
{
	BOOST
	int n;
	cin>>n;
	for(int i = 0 ; i < n ; i++)
		cin>>T[i];
	int ans = INF;
	dp[0][1]=1;
	dp[0][2]=1;
	for(int i = 1 ; i< n ; i++)
	{
		if(i&1)
		{
			if(T[i]<=T[i-1])
				dp[i][0]=dp[i-1][1];
			else
				dp[i][0]=min(dp[i-1][0] ,dp[i-1][1]);
			dp[i][1]=dp[i-1][1]+1;
			dp[i][2]=min(min(dp[i-1][0] ,dp[i-1][1] ) ,dp[i-1][2] )+1;
		}
		else
		{
			if(T[i]>=T[i-1])
				dp[i][0]=dp[i-1][2];
			else
				dp[i][0]=min(dp[i-1][0] ,dp[i-1][2]);
			dp[i][2]=dp[i-1][2]+1;
			dp[i][1]=min(min(dp[i-1][0] ,dp[i-1][2] ) ,dp[i-1][1] )+1;
		}
	}
	ans = min(min(dp[n-1][0] , dp[n-1][1]) , dp[n-1][2]);
	for(int i = 1 ; i< n ; i++)
	{
		if(!(i&1))
		{
			if(T[i]<=T[i-1])
				dp[i][0]=dp[i-1][1];
			else
				dp[i][0]=min(dp[i-1][0] ,dp[i-1][1]);
			dp[i][1]=dp[i-1][1]+1;
			dp[i][2]=min(min(dp[i-1][0] ,dp[i-1][1] ) ,dp[i-1][2] )+1;
		}
		else
		{
			if(T[i]>=T[i-1])
				dp[i][0]=dp[i-1][2];
			else
				dp[i][0]=min(dp[i-1][0] ,dp[i-1][2]);
			dp[i][2]=dp[i-1][2]+1;
			dp[i][1]=min(min(dp[i-1][0] ,dp[i-1][2] ) ,dp[i-1][1] )+1;
		}
	}
	ans = min(ans,min(min(dp[n-1][0] , dp[n-1][1]) , dp[n-1][2]));
	
	cout<<ans<<'\n';
	return 0;
}