#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; i++)
using namespace std;

typedef long long ll;

int main() {
    int N;
    cin >> N;
    vector<int> A(N);
    rep(i, N) cin >> A[i];
    int ok = 0, ng = (N - 1) / 2 + 1;
    while (ok + 1 < ng) {
        int mi = (ok + ng) / 2;
        int i = 1;
        vector<int> v = {A[0]};
        bool f = false;
        while (i < N) {
            int j = lower_bound(v.begin(), v.end(), A[i]) - v.begin();
            if (j == v.size()) {
                v.push_back(A[i]);
                if (v.size() == mi + 1) {
                    f = true;
                    break;
                }
            } else {
                v[j] = min(v[j], A[i]);
            }
            i++;
        }
        if (f) {
            v = {-A[i]};
            i++;
            f = false;
            while (i < N) {
                int j = lower_bound(v.begin(), v.end(), -A[i]) - v.begin();
                if (j == v.size()) {
                    v.push_back(-A[i]);
                    if (v.size() == mi + 1) {
                        f = true;
                        break;
                    }
                } else {
                    v[j] = min(v[j], -A[i]);
                }
                i++;
            }
            if (f) {
                ok = mi;
                continue;
            }
        }
        i = 1;
        v = {-A[0]};
        f = false;
        while (i < N) {
            int j = lower_bound(v.begin(), v.end(), -A[i]) - v.begin();
            if (j == v.size()) {
                v.push_back(-A[i]);
                if (v.size() == mi + 1) {
                    f = true;
                    break;
                }
            } else {
                v[j] = min(v[j], -A[i]);
            }
            i++;
        }
        if (f) {
            v = {A[i]};
            i++;
            f = false;
            while (i < N) {
                int j = lower_bound(v.begin(), v.end(), A[i]) - v.begin();
                if (j == v.size()) {
                    v.push_back(A[i]);
                    if (v.size() == mi + 1) {
                        f = true;
                        break;
                    }
                } else {
                    v[j] = min(v[j], A[i]);
                }
                i++;
            }
            if (f) {
                ok = mi;
                continue;
            }
        }
        ng = mi;
    }
    cout << ok << "\n";
}