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#include <iostream>
#include <ctime>
#include <vector>

using namespace std;
/**
5
4 1 3 3 1
ANS: 1
*/
int main() {
    clock_t start = clock();
    int n, k;
    cin >> n;
    std::vector<int> arr;
    for(int i = 0; i < n; i++) {
       cin >> k;
       arr.push_back(k);
    }


    bool nextSmaller = true;
    int changes = 0;
    for(int i = 0; i < n - 1; i++) {
        if((arr[i] > arr[i + 1] && nextSmaller) || (arr[i] < arr[i + 1] && !nextSmaller)) {
            nextSmaller = !nextSmaller;
        } else {
            changes++;
            i++;
        }
    }

    bool nextSmaller2 = false;
    int changes2 = 0;
    for(int i = 0; i < n - 1; i++) {
        if((arr[i] > arr[i + 1] && nextSmaller2) || (arr[i] < arr[i + 1] && !nextSmaller2)) {
            nextSmaller2 = !nextSmaller2;
        } else {
            changes2++;
            i++;
        }
    }


    cout << min(changes, changes2) << endl;
    return 0;
}