#include<fstream>
#include<algorithm>
#include<vector>
#define NMAX 5005
#define INF (1<<30)
using namespace std;
FILE *fin,*fout;
int a[NMAX],n,sol=INF,m,v[NMAX];
vector<int> S;
inline void read()
{
	fin=fopen("secv.in","r");
	fscanf(fin,"%d",&n);
	for(int i=1;i<=n;i++)
	{
		fscanf(fin,"%d",&a[i]);
		v[i]=a[i];
	}
	fclose(fin);
}
inline void print()
{
	fout=fopen("secv.out","w");
	if(sol==INF)
		sol=-1;
	fprintf(fout,"%d",sol);
	fclose(fout);
}
void normalize()
{
	v[0]=-1;
	sort(v+1,v+n+1);
	for(int i=1;i<=n;i++)
		if(v[i]!=v[i-1])
			S.push_back(v[i]);
}
void solve()
{
	int i,j;
	size_t k;
	for(i=1;i<=n;i++)
		if(a[i]==S[0])
		{
			if(S.size()<=1)
			{
				sol=1;
				break;
			}
			for(j=i+1,k=1;j<=n;j++)
			{
				if(a[j]==S[k])
					k++;
				if(k>=S.size())
				{
					sol=min(sol,j-i+1);
					break;
				}
			}
		}
}
int main()
{
	read();
	normalize();
	solve();
	print();
	return 0;
}