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

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n = 0;
    cin >> n;
    int T[n];
    int T2[n];
    for (int i = 0; i < n; i++) {
        cin >> T[i];
        T2[i] = T[i];
    }
    int wynik = 0;
    bool d = 1;
    if (T2[0] == 1000000000) {
        wynik++;
        T2[0] = -1000000000;
    }
    for (int i = 1; i < n; i++) {
        //cout << d << ' ' << T2[i]  << ' ' << T2[i-1] << endl;
        if (d && T2[i] <= T2[i-1]) {
            wynik++;
            T2[i] = 1000000000;
        }
        else if (!d && T2[i] >= T2[i-1]) {
            wynik++;
            T2[i] = -1000000000;
        }
        d = !d;
    }
    //cout << wynik << endl;
    for (int i = 1; i < n; i++) {
        T2[i] = T[i];
    }
    int wynik1 = 0;
    d = 0;
    if (T2[0] == -1000000000) {
        wynik++;
        T2[0] = 1000000000;
    }
    for (int i = 1; i < n; i++) {
        //cout << d << ' ' << T2[i]  << ' ' << T2[i-1] << endl;
        if (d && T2[i] <= T2[i-1]) {
            wynik1++;
            T2[i] = 1000000000;
        }
        else if (!d && T2[i] >= T2[i-1]) {
            wynik1++;
            T2[i] = -1000000000;
        }
        d = !d;
    }
    //cout << wynik1 << endl;
    cout << min(wynik, wynik1);
}