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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(1); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=50100;
int n,b[N][3],dp[N][3],a[N];
int solve() {
	rep(i,0,n) {
		b[i][0]=a[i],b[i][1]=1e9,b[i][2]=-1e9;
		dp[i][0]=dp[i][1]=dp[i][2]=1e9;
	}
	dp[0][0]=0;
	dp[0][1]=1;
	dp[0][2]=1;
	rep(i,1,n) rep(j,0,3) rep(k,0,3) {
		if ((i%2==1&&b[i-1][j]<b[i][k])||
			(i%2==0&&b[i-1][j]>b[i][k]))
			dp[i][k]=min(dp[i][k],dp[i-1][j]+(k!=0));
	}
	return min({dp[n-1][0],dp[n-1][1],dp[n-1][2]});
}

int main() {
	scanf("%d",&n);
	rep(i,0,n) scanf("%d",&a[i]);
	int ans=solve();
	rep(i,0,n) a[i]=-a[i];
	ans=min(ans,solve());
	printf("%d\n",ans);
}