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#include <iostream>
#include <vector>
#include <algorithm>

#define lol long long
#define def_times(a, b) int a = 0; a<b; a++

using namespace std;


inline const lol tmax =  1000 * 1000 * 1000;
inline const lol tmin = -1000 * 1000 * 1000;

int main()
{
	int n;
	cin >> n;
	vector<lol> twit(n);
	for(def_times(i, n))
		cin >> twit[i];
	
	int sol1 = 0;
	lol last = twit[0];
	if(last != tmax)
		for(def_times(i, n-1))    // i%2==0 => rosn.
		{
			if(i%2==0)
			{
				if(last >= twit[i+1])
				{
					last = tmax;
					sol1++;
				}
				else
					last = twit[i+1];
			}
			else
			{
				if(last <= twit[i+1])
				{	
					last = tmin;
					sol1++;
				}
				else
					last = twit[i+1];
			}
		}
	else
		sol1 = INT32_MAX;
		
	int sol2 = 0;
	last = twit[0];
	if(last != tmin)
		for(def_times(i, n-1))    // i%2==0 => mal.
		{
			if(i%2==0)
			{
				if(last <= twit[i+1])
				{
					last = tmin;
					sol2++;
				}
				else
					last = twit[i+1];
			}
			else
			{
				if(last >= twit[i+1])
				{
					last = tmax;
					sol2++;
				}
				else
					last = twit[i+1];
			}
		}
	else
		sol2 = INT32_MAX;

	cout << (sol1>sol2 ? sol2 : sol1);
}