#include <fstream>
#include <set>
#define nmax 5005

using namespace std;

ifstream in("secv.in");
ofstream out("secv.out");

set <int> s;
set <int> ::iterator it;

int st, dr, lung=nmax, n ;

int v[nmax];

int main()
{
    in>>n;
    for(int i=1; i<=n; i++)
    {
        in>>v[i];
        s.insert(v[i]);
    }
    for(st=1; st<=n; st++)
    {
        it = s.begin();
        for(dr =st; dr<=n && it!=s.end(); dr++)
        {
            if(v[dr]==(*it))
                it++;
        }
        dr--;
        if(it==s.end())
        {
            lung = min(lung, dr-st+1);
        }
    }
    if(lung ==nmax)
        out<<-1;
    else
        out<<lung;
    return 0;
}