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#include <bits/stdc++.h>
using namespace std;

#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define F first
#define S second
#define pb push_back
#define eb emplace_back
#define mkp make_pair
#define pque priority_queue
#define vt vector
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define END(x) { cout << x; return; }

template<int D, typename T> struct vtd : public vector<vtd<D - 1, T>> { 
	template<typename... Args> vtd(int n = 0, Args... args) : vector<vtd<D - 1, T>>(n, vtd<D - 1, T>(args...)) {} };
template<typename T> struct vtd<1, T> : public vector<T> { vtd(int n = 0, const T& val = T()) : vector<T>(n, val) {} };

#define PI (ld)3.1415926535897932384626433832795
#define MOD (int)1000000007
#define inf (int)1000000000
#define INF (ll)1000000000000000001
#define EPS 1e-9

typedef long double ld;
typedef long long ll;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair <int, int> pii;
typedef pair <ll, ll> pll;

#ifdef NOT_OJ
	#define debug(x) cerr << #x << ": "; __print(x); cerr << "\n";
#else
	#define debug(x)
#endif

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void __print(ll t) { cerr << t; }
void __print(int t) { cerr << t; }
void __print(string t) { cerr << t; }
void __print(char t) { cerr << t; }
void __print(ld t) { cerr << t; }
void __print(double t) { cerr << t; }
void __print(ull t) { cerr << t; }
void __print(uint t) { cerr << t; }
void __print(bool t) { cerr << t; }

template <class T, class V> void __print(pair <T, V> p);
template <class T> void __print(vt <T> v);
template <class T> void __print(set <T> v);
template <class T, class V> void __print(map <T, V> v);
template <class T> void __print(multiset <T> v);
template <class T> void __print(vt <vt <T>> v);
template <int D, class T> void __print(vt <vtd <D, T>> v);
template <class T> void __print(unordered_set <T> v);
template <class T, class V> void __print(unordered_map <T, V> v);
template <class T, class V> void __print(pair <T, V> p) {cerr << "{"; __print(p.F); cerr << ","; __print(p.S); cerr << "}";}
template <class T> void __print(vt <T> v) {cerr << "[ "; for (T i : v) {__print(i); cerr << " ";} cerr << "]";}
template <class T> void __print(vt <vt <T>> v) {cerr << "\n"; for (int i = 0; i < sz(v); i++) {cerr << "  "<< i << ": "; __print(v[i]); cerr << "\n";}}
template <int D, class T> void __print(vt <vtd <D, T>> v) {cerr << "\n"; for (int i = 0; i < sz(v); i++) {cerr << "  "<< i << ": "; __print(v[i]); cerr << "\n";}}
template <class T> void __print(set <T> v) {cerr << "[ "; for (T i : v) {__print(i); cerr << " ";} cerr << "]";}
template <class T> void __print(unordered_set <T> v) {cerr << "[ "; for (T i : v) {__print(i); cerr << " ";} cerr << "]";}
template <class T> void __print(multiset <T> v) {cerr << "[ "; for (T i : v) {__print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void __print(map <T, V> v) {cerr << "[ "; for (auto i : v) {__print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void __print(unordered_map <T, V> v) {cerr << "[ "; for (auto i : v) {__print(i); cerr << " ";} cerr << "]";}

int solve(vt <int> &v, bool at) {
    int ans = 0, prev = v[0];
    for (int i = 1; i < sz(v); i++) {
        int x = v[i];
        if (at) { // prev > x
            if (prev <= x) { ans++; prev = -inf; }
            else prev = x;
        }
        else { // prev < x
            if (prev >= x) { ans++; prev = inf; }
            else prev = x;
        }
        at = 1 - at;
    }
    return ans;
}

void __runcase() {
    int n;
    cin >> n;
    vt <int> v(n);
    for (auto &x : v) cin >> x;
    cout << min(solve(v, 0), solve(v, 1)) << "\n";
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(NULL);
	
	int __test_cases = 1;
	// cin >> __test_cases;

	while(__test_cases--) {
		__runcase();
	}
}