#include<iostream>
#include<math.h>
#define max 105

using namespace std;

int main(){
	int n;
	cin>>n;
	int arr[max];
	int freq[max];
	for(int i=0;i<=100;i++){
		freq[i] = 0;
	}
	for(int i=0;i<n;i++){
		cin>>arr[i];
	}
	
	for(int i=0;i<n;i++){
		freq[arr[i]]++;
	//	cout<<freq[arr[i]]<<"  ";
	}
//	cout<<endl;
	int lar = -1;
	int num;
	for(int i=0;i<100;i++){
		num = freq[i] + freq[i+1];
		if(lar<num){
			lar = num;
		}
	}
	cout<<lar<<endl;
}