#include <fstream>

using namespace std;
ifstream f("subsir2.in");
ofstream g("subsir2.out");
int l[5001],a[5001],bf[5001],n,lmax,i;
int verif(int i)
{
    for(int j=1;j<i;j++)
        if(a[j]<a[i]) return 0;
    return 1;
}
int valid (int i,int j)
{
    for(int w=i+1;w<j;w++)
        if(a[w]>=a[i]&&a[w]<=a[j]) return 0;
    return 1;
}
void solve()
{
    int i,j,mn,poz,mina=1000001,pozm,s,p;
    l[n]=1;
    for(i=n-1;i>=1;i--)
    {
         mn=1000001;
         s=1000001;
        for(j=i+1;j<=n;j++)
        {
            if(a[i]<=a[j]&&mn>a[j])
                {mn=a[j];
                if(l[j]<=s) s=l[j],p=j;}
        }
        if(mn==1000001) l[i]=1;
        else l[i]=1+l[p],bf[i]=p;
    }

    g<<mn<<'\n';
}
int main()
{
    f>>n;
    for(i=1;i<=n;i++) f>>a[i];

    solve();
    return 0;
}