#include <bits/stdc++.h>

using namespace std;

int n;
int v[5003];
int aux[5003];

int main()
{
    freopen("secv.in","r",stdin);
    freopen("secv.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		scanf("%d",&v[i]);
		aux[i]=v[i];
	}
	sort(aux+1,aux+n+1);
	vector<int>x;
	x.push_back(aux[1]);
	for(int i=2;i<=n;i++){
		if(aux[i]!=aux[i-1]){
			x.push_back(aux[i] );
		}
		
	}
	int hmin=INT_MAX;
	for(int i=1;i<=n;i++){
		if(v[i] == x[0]){
			int k=1,j;
			for(j=i+1;j<=n && k<(int)x.size();j++)
				if(v[j]==x[k])
					k++;
			if(k==(int) x.size()){
				hmin=min(hmin,j-i);
			}
		}
	}
	if(hmin==INT_MAX)printf("-1");
	else printf("%d\n",hmin);


    return 0;
}