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#include <iostream>

constexpr int maxN = 5e4;
constexpr int MAX = 1e9;

int n;
int a[maxN + 1];

int solve(bool dir) {
    int last = a[1];
    int res = 0;

    for(int i=2; i<=n; i++) {
        if(dir) {
            if(last < a[i]) {
                last = a[i];
            }
            else {
                last = MAX;
                res++;
            }
        }
        else {
            if(last > a[i]) {
                last = a[i];
            }
            else {
                last = -MAX;
                res++;
            }
        }

        dir = !dir;
    }

    return res;
}

int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(NULL);
    std::cout.tie(NULL);

    std::cin >> n;

    for(int i=1; i<=n; i++) {
        std::cin >> a[i];
    }

    std::cout << std::min(solve(0), solve(1));
}