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#include <stdio.h>
#include <algorithm>
const int C=1000001;

int a[C], seq[C];
int main(){
	int n, diff;
	scanf ("%d", &n);
	for (int i=0; i<n; i++) scanf ("%d", &a[i]);

	for (int i=1; i<n; i++){
		diff = a[i] - a[i-1];
		if (diff > 0) seq[i] = 2;
		else if (diff == 0) seq[i] = 1;
		else seq[i] = 0;
	}

	int res_1 = 0, res_2 = 0;
	for (int i=1; i<n; ){
		if (i%2 == 0 && seq[i] != 0){
			res_1 += 1;
			i+=2;
		}
		else if (i%2 == 1 && seq[i] != 2){
			res_1 += 1;
			i+=2;
		}
		else i++;
	}

	for (int i=1; i<n; ){
		if (i%2 == 0 && seq[i] != 2){
			res_2 += 1;
			i+=2;
		}
		else if (i%2 == 1 && seq[i] != 0){
			res_2 += 1;
			i+=2;
		}
		else i++;
	}

	printf ("%d\n", std::min(res_1, res_2));
return 0;}