import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	}

} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	} main {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int[] p = new int[n]; p new int[n] n for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		} int i=0; int i=0; i 0 i<n i n i++ i++ i {
			p[i] = sc.nextInt();
		} {
			p[i] = sc.nextInt();
		} p[i] = sc.nextInt() p[i] p i sc.nextInt() sc.nextInt sc int cnt = 0; cnt 0 int flg = 0; flg 0 if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		} p[0]>p[1] p[0] p 0 p[1] p 1 {
			flg = 0;
		} flg = 0 flg 0 {
			flg = 1;
		} flg = 1 flg 1 for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		} int i=1; int i=1; i 1 i<n-1 i n-1 n 1 i++ i++ i {
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		} {
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		} if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			} flg==0 && p[i]>p[i+1] flg==0 flg 0 p[i]>p[i+1] p[i] p i p[i+1] p i+1 i 1 {
				cnt += 1;
				flg = 0;
			} cnt += 1 cnt 1 flg = 0 flg 0 if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			} flg==0 && p[i]<p[i+1] flg==0 flg 0 p[i]<p[i+1] p[i] p i p[i+1] p i+1 i 1 {
				flg=1;
			} flg=1 flg 1 if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			} flg==1 && p[i]>p[i+1] flg==1 flg 1 p[i]>p[i+1] p[i] p i p[i+1] p i+1 i 1 {
				flg=0;
			} flg=0 flg 0 if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			} flg==1 && p[i]<p[i+1] flg==1 flg 1 p[i]<p[i+1] p[i] p i p[i+1] p i+1 i 1 {
				cnt +=1;
				flg = 1;
			} cnt +=1 cnt 1 flg = 1 flg 1 System.out.println(cnt) System.out.println System.out System System.out cnt String[] args args public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	}

} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();
		int[] p = new int[n];
		for(int i=0; i<n; i++){
			p[i] = sc.nextInt();
		}

		int cnt = 0;
		int flg = 0;
		if(p[0]>p[1]){
			flg = 0;
		}else{
			flg = 1;
		}
		for(int i=1;i<n-1;i++){
			if(flg==0 && p[i]>p[i+1]){
				cnt += 1;
				flg = 0;
			}else if(flg==0 && p[i]<p[i+1]){
				flg=1;
			}else if(flg==1 && p[i]>p[i+1]){
				flg=0;
			}else if(flg==1 && p[i]<p[i+1]){
				cnt +=1;
				flg = 1;
			}
		}
		System.out.println(cnt);

	}

}
