#include <bits/stdc++.h>
using namespace std ;
const int NR = 5005 , oo = 5005 ;
ifstream in ("secv.in") ;
ofstream out ("secv.out") ;
int v [ NR ] , p [ NR ] , n , r [ NR ] , cnt = 1 , sw [ NR ] , sol = oo ;
vector < int > d ( NR , oo ) ;
inline bool cmp ( const int i , const int j )   {
    return v [ i ] < v [ j ] ;
}
int main ()
{
    int i ;
    in >> n ;
    for ( i = 1 ; i <= n ; ++ i )   {
        in >> v [ i ] ;
        p [ i ] = i ;
    }
    sort ( p + 1 , p + n + 1 , cmp ) ;
    r [ p [ 1 ] ] = 1 ;
    for ( i = 2 ; i <= n ; ++ i )   {
        if ( v [ p [ i ] ] != v [ p [ i - 1 ] ] )
            r [ p [ i ]  ] = ++ cnt ;
        else
            r [ p [ i ]  ] = cnt ;
    }   // r  este de fapt v normalizat
        // sw [ i ] - ultima pozitie pe care apare i daca exista subsirul 1 - i
    for ( i = 1 ; i <= n ; ++ i )   {
        if ( r [ i ] == 1 ) sw [ 1 ] = i , d [ 1 ] = 1 ;
        if ( sw [ r [ i ] - 1 ] )   d [ r [ i ] ] = i - sw [ r [ i ] - 1 ] + d [ r [ i ] - 1 ] , sw [ r [ i ] ] = i ;
        if ( r [ i ] == cnt )   sol = min ( sol , d [ cnt ] ) ;
    }
    if ( sol == oo )    out << -1 ;
    else                out << sol ;
}