#include <fstream>
#include <set>


using namespace std;

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

const int NMAX = 5000;

int n;
int v[NMAX + 5];
set<int> elem;
int sol = 1e9;

int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> v[i];
        elem.insert(v[i]);
    }
    set<int>::iterator it;
    it = elem.begin();

    for (int i = 1; i <= n; i++)
    {
        it = elem.begin();
        for (int j = i; j <= n; j++)
        {
            if (v[j] == *it)
                it++;
            if (it == elem.end())
            {
                sol = min(sol, j - i + 1);
                it = elem.begin();
                break;
            }
        }
    }
    if (sol == 1e9)
        sol = -1;
    cout << sol;
    return 0;
}