CF 2014 E

#include<bits/stdc++.h>
 
#define int long long int
#define rep(a,b,c) for(int a=b;a<c;a++)
#define repm(a,b,c) for(int a=(b-1);a>=c;a--)
#define pb push_back
#define str string
#define sf(a) scanfs("%d",&a)
#define pb push_back
#define mp make_pair
#define Fi first
#define Se second
#define ALL(v) (v).begin(), (v).end()
 
using namespace std;
 
const int INF = 1e18 + 9;
const int Mod = 1e9 + 7;
inline int replac(str s){double ans=0;rep(i,0,s.length()){ans+=(s[i]-'0')*pow(10,s.length()-i-1);}return (int)ans;}
inline string numstr(int m){str s="";while(m>0){char c;int a=m/10;if(a>0)a=m%(a*10);else a=m;c=(char)('0'+a);s+=c;m/=10;}str st="";for(int i=s.size()-1;i>=0;i--){st+=s[i];}return st;}
typedef vector<int> vi;
typedef pair<int,int> pii;
typedef vector<pii> vii;
int n,mu[3003];
int nu[3003][3003][2];
int f(int num,int m,bool up){
    if(nu[num][m][up]>-1){
        return nu[num][m][up];
    }
    if(num>=n)return nu[num][m][up]=0;
    else{
        int ans=0;
        if(up&&mu[num]>mu[m]){
            ans=max(f(num+1,num,!up)+1,f(num+1,m,up));
        }else if(!up&&mu[num]<mu[m]){
            ans=max(f(num+1,num,!up)+1,f(num+1,m,up));
        }else{
            ans=f(num+1,m,up);
        }
        return nu[num][m][up]=ans;
    }
}
signed main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    rep(i,0,3001){
        rep(j,0,3001){
            rep(k,0,2){
                nu[i][j][k]=-1;
            }
        }
    }
    cin >> n;
    rep(i,0,n){
        cin >> mu[i];
    }
    int ans=max(f(0,0,false),f(0,0,true))+1;
    if(ans<=2){
        cout << 0 << endl;
    }else{
        cout << ans << endl;
    }
    return 0;
}