#include <bits/stdc++.h>
#include <chrono>
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<58);

template<class T> bool chmin(T &a, const T &b){
    if(a > b) {a = b; return true;}
    else return false;
}
template<class T> bool chmax(T &a, const T &b){
    if(a < b) {a = b; return true;}
    else return false;
}

void up(vec &a, vec &memo){
    vec left(0);
    rep(i,N){
        auto ite = upper_bound(ALL(left), a[i]);
        memo[i] = ite - left.begin();
        if(ite == left.begin()){
            if(left.empty()) left.push_back(a[i]);
            else chmin(left[0], a[i]);
        }else{
            if(ite == left.end()){
                if(*left.rbegin() < a[i]) left.push_back(a[i]);
            }else{
                --ite;
                if(*ite < a[i]) left[(ite - left.begin()) + 1] = a[i];
            }
        }
    }
}

int main() {
    cin>>N;
    vec a(N);
    rep(i,N) cin>>a[i];
    vec lu(N), ru(N), ld(N), rd(N);
    up(a, lu);
    reverse(ALL(a));
    up(a, ru);
    reverse(ALL(ru));
    rep(i, N) a[i] = -a[i];
    up(a, rd);
    reverse(ALL(rd));
    reverse(ALL(a));
    up(a, ld);
    ll ans = 0;
    rep(i,N) chmax(ans, max(min(lu[i], ru[i]), min(ld[i], rd[i])));
    cout<<ans<<endl;
}