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#include <stdio.h>

#define MAX_NUM 1000000000

int nums[50000];

int ans(int n, int sign)
{
	int last = sign * MAX_NUM;
	int res = 0;

	for (int i = 0; i < n; i++) {
		if (sign * (last - nums[i]) > 0) {
			last = nums[i];
		} else {
			last = -sign * MAX_NUM;
			res++;
		}
		sign = -sign;
	}

	return res;
}

int main(void)
{
	int n;

	scanf("%d", &n);
	for (int i = 0; i < n; i++)
		scanf("%d", &nums[i]);

	int ansp = ans(n, +1);
	int ansn = ans(n, -1);

	printf("%d\n", ansp < ansn ? ansp : ansn);
}