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#include <iostream>

int kk = 1000001;
int n;

int main() {
    std::ios_base::sync_with_stdio(0);
    std::cin >> n;
    int dir = 1;
    int sum1 = 0;
    int sum2 = 0;
    int wp1;
    std::cin >> wp1;
    int wp2 = wp1;
    for (int i=1;i<n;++i) {
        int w;
        std::cin >> w;
        if ((w-wp1)*dir <= 0) {
            ++sum1;
            wp1 = dir*kk;
        } else wp1 = w;
        if ((wp2-w)*dir <= 0) {
            ++sum2;
            wp2 = -dir*kk;
        } else wp2 = w;
        dir = -dir;
    }
    std::cout << std::min(sum1, sum2) << std::endl;

    return 0;
}