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#include <iostream>
#include <vector>

using namespace std;

// #define DEBUG
#ifdef DEBUG
#define dassert(x) assert(x);
#define df(...) printf(__VA_ARGS__)
#else
#define dassert(x)
#define df(...)
#endif

#define x first
#define y second
#define mp make_pair
#define pb push_back
#define ir(x, a, b) ((a) <= (x) && (x) <= (b))
#define vec vector
#define sz(x) (ll)x.size()
#define foru(i, n) for (int i = 0; (i) < (n); ++(i))
#define all(x) (x).begin(), (x).end()

typedef int64_t ll;

int read() {
    int n = 0; bool b = 0; char c = getchar();
    for (; !ir(c, '0', '9'); c = getchar()) b = (c == '-');
    for (; ir(c, '0', '9'); c = getchar()) n = 10*n + (c-'0');
    if (b) return -n;
    return n;
}

int calc(const vec<int>& a, int n) {
    int wrong = 0, s = 0;
    foru (i, n-1) {
        if (a[i] != a[i+1] && ((a[i] > a[i+1]) ^ (i%2))) {
            // cout << "1 ";
            s += (wrong+1)/2;
            // if (wrong) df("wrong: %d (add %d)\n", wrong, (wrong+1)/2);
            wrong = 0;
        } else {
            // cout << "0 ";
            ++wrong;
        }
    }
    // cout << endl;
    // df("wrong: %d\n", wrong);
    s += (wrong+1)/2;
    return s;
}

int main() {
    df("debug mode\n");
#ifndef DEBUG
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#endif
    int n;
    cin >> n;
    vec<int> a(n);
    foru (i, n) cin >> a[i];
    
    int best = calc(a, n);
    df("%d\n", best);
    foru (i, n) a[i] = -a[i];
    int _temp;
    best = min(best, _temp = calc(a, n));
    df("%d\n", _temp);
    
    cout << best << "\n";
    return 0;
}