#include <fstream>
#include <unordered_set>

using namespace std;

ifstream in("secv.in");
ofstream out("secv.out");
int n, distincte;
int ans;
int v[5005];
pair<int, int> dp[5005];
unordered_set<int> s;

int main()
{
    in>>n;

    for(int i = 1; i<=n; i++)
    {
        in>>v[i];

        s.insert(v[i]);
    }

    distincte = s.size();

    for(int i = 1; i<=n; i++)
    {
        dp[i] = {1, 0};

        for(int j = 1; j<i; j++)
        {
            if(v[j] < v[i])
            {
                if(dp[j].first + 1 >= dp[i].first)
                {
                    dp[i].first = dp[j].first + 1;
                    dp[i].second = j;
                }
            }
        }
    }

    ans = (1 << 30);
    for(int i = 1; i<=n; i++)
    {
        //out<<dp[i].first<<" "<<dp[i].second<<'\n';

        if(dp[i].first == distincte)
        {
            int poz = i;
            while(dp[poz].second != 0)
            {
                poz = dp[poz].second;
            }

            ans = min(ans, i - poz + 1);
        }
    }

    if(ans == (1 << 30))
    {
        out<<-1;
    }
    else
    {
        out<<ans;
    }

    return 0;
}