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#include <iostream>
int n;
int tab[50001];
int counter[2];
int last[2];
int MAX_VAL = 1e9;
int MIN_VAL = -1e9;
using namespace std;
int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> tab[i];
    }
    last[0] = tab[1];
    last[1] = tab[1];
    for (int i = 2; i <= n; i++) {
        counter[i % 2] += (tab[i] > last[i % 2] ? 0 : 1);
        last[i % 2] = (tab[i] > last[i % 2] ? tab[i] : MAX_VAL);
        counter[(i+1) % 2] += (tab[i] < last[(i+1) % 2] ? 0 : 1);
        last[(i+1) % 2] = (tab[i] < last[(i+1) % 2] ? tab[i] : MIN_VAL);
    }
    cout << min(counter[0], counter[1]) << endl;
    return 0;
}