#include<stdio.h>
#include<stdlib.h>
#define N 10000
int v[5000],w[5000],n,i,j,q;
int comp(const void *a,const void *b){
	return *(int *)a-*(int *)b;
}
int cauta(int x){
	for(int i=0;i<q;++i)
		if(w[i]==x)
			return 0;
	return 1;
}
int main () {
	freopen("secv.in","r",stdin);
	freopen("secv.out","w",stdout);
	int x,k,min=N;
	scanf("%d",&n);
	for(i=0;i<n;++i){
		scanf("%d",&v[i]);
		if(cauta(v[i]))
			w[q++]=v[i];
	}
	qsort(w,q,sizeof(int),comp);
	for(i=0;i<n;++i)
		if(v[i]==w[0]){
			x=1;
			k=i;
			for(j=i+1;j<n;++j)
				if(v[j]==w[x]){
					++x;
					k=j;
				}
			if(v[k]==w[q-1])
				if(k-i+1<min)
					min=k-i+1;
		}
	if(min==N)
		printf("-1\n");
	else
		printf("%d\n",min);
	return 0;
}