#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,i;
    cin >> n;
    vector<int> a(n);
    for(int i = 0;i < n;i++){
       cin >> a[i];
    }
    sort(a.begin(), a.end());
    int start=0, end =1, max =INT_MIN;
    while(end<n){
        if((a[end] - a[start]) <=1) end++;
        else {
            start++;
            end = start+1;
        }
        if(max < (end-start))
            max = end-start;
    }

    cout<<max;
    return 0;
}