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#include<bits/stdc++.h>

#define st first
#define nd second
#define pb(x) push_back(x)
#define pp(x) pop_back(x)
#define mp(a, b) make_pair(a, b)
#define all(x) (x).begin(), (x).end()
#define rev(x) reverse(all(x))
#define sor(x) sort(all(x))
#define sz(x) (int)(x).size()
#define rsz(x) resize(x)

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii > vii;
typedef vector<ll> vl;
typedef vector<pll> vll;
typedef string str;
#define BOOST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL); 
const int MN = 50009; 
int tab[MN];
int n; 
const int INF = 10000009; 
void read(){ 
	cin >> n; 
	for(int i = 0;i < n; i++) 
		cin >> tab[i]; 
} 
void run(){ 
	int w1 = 0, w2 = 0; 
	int aktu = tab[0];  
	//cout << aktu << ' '; 
	for(int i = 1; i < n; i++){  
		if((i & 1) && tab[i] <= aktu){ 
			aktu = INF; 
			w1++; 
		} 
		else if(!(bool)(i & 1) && tab[i] >= aktu){ 
			aktu  = - INF; 
			w1++; 
		} 
		else { 
			aktu = tab[i];  
		} 
		//cout << aktu << ' '; 
	}  
	//cout << "\n"; 
	aktu = tab[0];    
	//cout << aktu << ' '; 
	for(int i = 1; i < n; i++){ 
		if(!(bool)(i & 1) && tab[i] <= aktu){ 
			aktu = INF; 
			w2++; 
		} 
		else if((i & 1) && tab[i] >= aktu){ 
			aktu  = - INF; 
			w2++; 
		} 
		else { 
			aktu = tab[i];  
		} 
		//cout << aktu << ' '; 
	}  
	//cout << aktu << "\n"; 
	cout << min(w1, w2); 
	//cout << w1 << ' ' << w2;  
}
int main(){ 
	read(); 
	run(); 
}