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#include <cstdio>
#include <cassert>
#include <cstring>
#include <algorithm>

using namespace std;

const int max_size = 50005;

int n;
int t[max_size];

int calctab[3][max_size];

void calc()
{
	for(int i = n-2; i >= 0; --i) {
		int dir = -1;
		for(int j = 0; j < 2; ++j) {
			dir *= -1;
			if (t[i]*dir < t[i+1]*dir) {
				calctab[dir+1][i] = calctab[-dir+1][i+1];
			} else {
				calctab[dir+1][i] = 1 + min( calctab[-dir+1][i+1], calctab[dir+1][i+2] );
			}
		}
	}
}

int main()
{
        scanf("%d\n", &n);

	for(int i = 0; i < n; ++i) {
		scanf("%d", t+i);
	}
	calc();
	printf("%d\n",  min(calctab[0][0], calctab[2][0]));

        return 0;
}