#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int u, v, w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;
int INF = INT_MAX / 2;

struct segment_tree_max {
	int n; vector<short> v;
	segment_tree_max(int _n) {
		for (n = 1; n < _n; n *= 2);
		v = vector<short>(n * 2 - 1, 0);
	}
	void set(int i, short x) {
		int k = i + n - 1;
		v[k] = x;
		while (k > 0) {
			k = (k - 1) / 2;
			v[k] = max(v[k * 2 + 1], v[k * 2 + 2]);
		}
	}
	short _get(int i, int j, int k, int l, int r) {
		if (r <= i || j <= l) return 0;
		if (i <= l && r <= j) return v[k];
		short vl = _get(i, j, k * 2 + 1, l, (l + r) / 2);
		short vr = _get(i, j, k * 2 + 2, (l + r) / 2, r);
		return max(vl, vr);
	}
	short get(int i, int j) { return _get(i, j, 0, 0, n); }
};

int main() {
	int N; cin >> N;
	vector<int> A(N);
	for (int i = 0; i < N; i++)
		cin >> A[i];
	vector<segment_tree_max> st(N, segment_tree_max(N));
	vector< vector<short> > dp(N, vector<short>(N)), _dp = dp;
	for (int i = 0; i < N; i++)
		for (int j = N - 1; j > i; j--) {
			if (A[i] < A[j]) {
				dp[i][j] = st[i].get(j + 1, N) + 1;
				st[j].set(i, dp[i][j]);
			}
			if (A[i] > A[j]) {
				_dp[i][j] = st[j].get(0, i) + 1;
				st[i].set(j, _dp[i][j]);
			}
		}
	short maxi = 0;
	for (int i = 0; i < N; i++)
		for (int j = 0; j < N; j++)
			maxi = max(maxi, max(dp[i][j], _dp[i][j]));
	cout << maxi + 1 << endl;
}