#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;

int main(){
    int n,counter=0,diff=0,small=0,x,i;
    cin >> n;
    int arr[n];
    for(int i=0;i<n;i++)
            {
            cin>>arr[i];
    }
    sort(arr,arr+n);
        while (i <n)
            {
            counter=0;
                x=i;
                   while(arr[i]- arr[x]<=1)
                    {
                        counter++;
                        i++;
                    }
                   
                if(counter>small)
                            small =counter;
                    
        }
    cout<<small ;
    
    
    return 0;
}