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#include <bits/stdc++.h>
using namespace std;

void as_gr(int &a, int &b, int &x){
	if(a >= b){
		if(a == 1e9){
			a = -1e9;
			++x;
			if(b == -1e9){
				b = 1e9;
				++x;
			}
		}
		else {
			b = 1e9;
			++x;
		}
	}
}

void as_ls(int &a, int &b, int &x){
	if(a <= b){
		if(a == -1e9){
			a = 1e9;
			++x;
			if(b == 1e9){
				b = -1e9;
				++x;
			}
		}
		else {
			b = -1e9;
			++x;
		}
	}
}

int main(){
	ios_base::sync_with_stdio(0);
	int n;
	cin >> n;
	vector <int> a(n);
	for(int i = 0; i < n; ++i){
		cin >> a[i];
	}
	vector <int> b, c;
	int x = 0, y = 0;
	b = a;
	c = a;
	for(int i = 0; i + 1 < n; ++i){
		if(i % 2 == 0){
			as_gr(b[i],b[i+1],x);
		}
		else if(i % 2 == 1){
			as_ls(b[i],b[i+1],x);
		}
	}
	
	for(int i = 0; i + 1 < n; ++i){
		if(i % 2 == 0){
			as_ls(c[i],c[i+1],y);
		}
		else if(i % 2 == 1){
			as_gr(c[i],c[i+1],y);
		}
	}
	cout << min(x,y) << '\n';
}