#include<bits/stdc++.h>
#define init read()
using namespace std;
int n,ans=0;
vector<int>vec;
inline int read()
{
	int mmm=0,ff=1;char xx=getchar();
	while((xx<'0'||xx>'9')&&xx!='-')xx=getchar();
	if(xx=='-')ff=-1,xx=getchar();
	while(xx>='0'&&xx<='9')
	mmm=mmm*10+xx-'0',xx=getchar();
	return mmm*ff;
}
inline void write(int x)
{
	if(x<0)
	{
		putchar('-');
		x=-x;
	}
	if(x>9)write(x/10);
	putchar('0'+x%10);
}
int main()
{
	//freopen("qoj1171.in","r",stdin);
	//freopen("qoj1171.out","w",stdout);
	n=init;
	for(int i=1;i<=n;i++)vec.emplace_back(init);
	if(vec.size()==1u)
	{
		puts("0");
		return 0;
	}
	int last=vec[0];bool up=true;
	for(int i=1;(unsigned)i<vec.size();i++)
	{
		int now=vec[i];
		if(now>=last&&up)
		{
			last=now;
			continue;
		}
		if(now<=last&&!up)
		{
			last=now;
			continue;
		}
		last=now;
		up=!up;ans++;
	}
	write((ans+1)>>1);putchar('\n');
	return 0;
}