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#include <vector>
#include <iostream>

int best(const std::vector<int> &ints, bool firstLower) {
    bool nextLower = firstLower;
    int left = ints[0];
    const int INFINITY = 10000000;
    int changes = 0;
    for (int i = 0; i < ints.size() - 1; i++) {
        if (left >= ints[i+1] && nextLower) {
            left = INFINITY;
            changes += 1;
        } else if (left <= ints[i+1] && !nextLower) {
            left = -INFINITY;
            changes += 1;
        } else {
            left = ints[i+1];
        }
        nextLower = !nextLower;
    }
    return changes;
}

int main() {
    int nints;
    scanf("%d", &nints);
    std::vector<int> ints(nints);

    for (int i = 0; i < nints; i++) {
        scanf("%d", &ints[i]);
    }

    int a = best(ints, false);
    int b = best(ints, true);

    printf("%d\n", std::min(a, b));
    return 0;
}