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#include <iostream>

using namespace std;

int n,a,b,ile_od_dolu,ile_od_gory,wyn_od_dolu,wyn_od_gory;

int sufit(int a,int b)
{
	if (a%b==0) return a/b;
	return a/b+1;
}

int min(int a,int b)
{
	if (a>b) return b;
	return a;
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin >> n >> a;
	for (int i=1 ; i<n ; i++)
	{
		b = a;
		cin >> a;
		if (i%2==0)
		{
			if (a<=b)
			{
				ile_od_gory++;
				wyn_od_dolu += sufit(ile_od_dolu,2);
				ile_od_dolu = 0;
			}
			if (a>=b)
			{
				ile_od_dolu++;
				wyn_od_gory += sufit(ile_od_gory,2);
				ile_od_gory = 0;
			}
		}
		else
		{
			if (a>=b)
			{
				ile_od_gory++;
				wyn_od_dolu += sufit(ile_od_dolu,2);
				ile_od_dolu = 0;
			}
			if (a<=b)
			{
				ile_od_dolu++;
				wyn_od_gory += sufit(ile_od_gory,2);
				ile_od_gory = 0;
			}
		}
	}
	cout << min(wyn_od_gory,wyn_od_dolu) << endl;
}