#include<bits/stdc++.h>
using namespace std;
int a[100000];
int main()
{
	int n;
	cin>>n;
	for(int i=0;i<n;i++) cin>>a[i];
	sort(a,a+n);
	int minn=0x3f3f3f,ans=0;
	for(int i=0;i<n;i++)
	{
		if(a[i]+1==a[i+1]) ans++;
		else if(ans+1!=1)minn=min(minn,ans+1),ans=0;
	}
	cout<<minn;
 	return 0;
}

_ 救救孩子吧 _