#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9+100;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;
int n;
int a[100005];

vector<int> lis(){
    vector<int> res(n);
    vector<int> lis(n,INF);
    rep(i,n){
        *lower_bound(lis.begin(),lis.end(),a[i]) = a[i];
        res[i]=lower_bound(lis.begin(),lis.end(),INF)-lis.begin();
    }
    return res;
}

int main(){
    scanf("%d",&n);
    rep(i,n) scanf("%d",&a[i]);
    int ans = 0;
    vector<int> b1 = lis();
    reverse(a,a+n);
    vector<int> b2 = lis();
    rep(i,n) a[i]*=-1;
    vector<int> c2 = lis();
    reverse(a,a+n);
    vector<int> c1 = lis();
    reverse(b2.begin(),b2.end());
    reverse(c2.begin(),c2.end());
    rep(i,n){
        ans = max(ans,min(b1[i],b2[i])-1);
        ans = max(ans,min(c1[i],c2[i])-1);
    }
    cout << ans << endl;
    return 0;
}