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

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    int n, a, prev_d, prev_u, res_d = 0, res_u = 0;
    cin >> n;
    cin >> a;
    prev_d = a; prev_u = a;
    for(int i=1; i<n; i++){
        cin >> a;
        if(i%2){
            if(prev_d <= a){
                res_d++;
                prev_d = -1000000000;
            }
            else{
                prev_d = a;
            }

            if(prev_u >= a){
                res_u++;
                prev_u = 1000000000;
            }
            else{
                prev_u = a;
            }
        }
        else{
            if(prev_d >= a){
                res_d++;
                prev_d = 1000000000;
            }
            else{
                prev_d = a;
            }

            if(prev_u <= a){
                res_u++;
                prev_u = -1000000000;
            }
            else{
                prev_u = a;
            }
        }
    }

    cout << min(res_d, res_u) << '\n';
}