#include <bits/stdc++.h>
using namespace std ;
const int NR = 5005 , oo = 5005 ;
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 ] ;
}
class InParser {
private:
	FILE *fin;
	char *buff;
	int sp;

	char read_ch() {
		++sp;
		if (sp == 4096) {
			sp = 0;
			fread(buff, 1, 4096, fin);
		}
		return buff[sp];
	}

public:
	InParser(const char* nume) {
		fin = fopen(nume, "r");
		buff = new char[4096]();
		sp = 4095;
	}

	InParser& operator >> (int &n) {
		char c;
		while (!isdigit(c = read_ch()) && c != '-');
		int sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}

	InParser& operator >> (long long &n) {
		char c;
		n = 0;
		while (!isdigit(c = read_ch()) && c != '-');
		long long sgn = 1;
		if (c == '-') {
			n = 0;
			sgn = -1;
		} else {
			n = c - '0';
		}
		while (isdigit(c = read_ch())) {
			n = 10 * n + c - '0';
		}
		n *= sgn;
		return *this;
	}
};
int main ()
{
    InParser in ("secv.in") ;
    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 ;
}