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#include "bits/stdc++.h" // Ignacy Boehlke
using namespace std;     // XIII LO Szczecin
template<class A,class B>ostream&operator<<(ostream&os,pair<A,B>p){return os<<'{'<<p.first<<", "<<p.second<<'}';}
template<class T>auto operator<<(ostream&os,T v)->decltype(v.end(),os){os<<'{';int i=0;for(auto e:v)os<<(", ")+2*!i++<<e;return os<<'}';}
#ifdef DEBUG
#define LOG(x...)cerr<<"["#x"]: ",[](auto...$){((cerr<<$<<"; "),...)<<'\n';}(x)
#else
#define LOG(...)(void)0
#endif
#define ssize(x)((int)x.size())
#define FOR(a,b,c)for(int a=(b);a<=(c);a++)
#define REP(a,b)FOR(a,0,(b)-1)
#define ALL(x)(x).begin(), (x).end()
#define fi first
#define se second
using ll=long long;

int main() {
	cin.tie(0)->sync_with_stdio(0);
	int n;
	cin >> n;
	vector<int> in(n);
	REP(i, n) cin >> in[i];
	vector<pair<int, int>> dp(n);
	dp[0] = {0, 1};
	dp[1] = {in[1] >= in[0], 1};
	FOR(i, 2, n - 1) {
		auto& d = dp[i];
		if (in[i - 2] < in[i - 1]) {
			if (in[i - 1] > in[i]) {
				d.fi = dp[i - 2].fi;
				d.se = d.fi + 1;
			} else {
				d.fi = d.se = dp[i - 2].fi + 1;
			}
		} else {
			if (in[i - 1] > in[i]) {
				d.fi = dp[i - 2].se;
				d.se = d.fi + 1;
			} else {
				d.fi = dp[i - 2].fi + 1;
				d.se = dp[i - 2].se + 1;
			}
		}
	}
	LOG(dp);
	cout << min({dp[n - 1].fi, dp[n - 2].se, (in[n - 1] > in[n - 2] ? dp[n - 2].fi : INT_MAX)}) << '\n';
}