#include <fstream>
#include <algorithm>

#define lmax 5001
#define maxim 10000000

using namespace std;

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

long long lungime=maxim,n,nr,i,j,ii;
long long v[lmax],vv[lmax],sol[lmax];

int main()
{
    f>>n;

    for (i=1;i<=n;i++)
     {
        f>>v[i];
        vv[i]=v[i];
     }

     sort(vv+1,vv+n+1);

     for (i=1;i<=n;i++)
      if (vv[i]!=vv[i-1])
       sol[++nr]=vv[i];

    for (ii=1;ii<=n;ii++)
      if (v[ii]==sol[1])
      {
          i=ii+1;
          j=2;

          while (i<=n && j<=nr)
            {
                if (v[i]==sol[j])
                 j++;

                i++;
            }

             if (j==nr+1)
              lungime=lungime<i-ii?lungime:i-ii;


      }
   if (lungime!=maxim)
    g<<lungime;
   else
    g<<-1;

    f.close();
    g.close();
}