#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, count = 1, max = 0, m;
    cin >> n;
    int a[n];
    for(i=0; i<n; i++)
        cin >> a[i];
    sort(a, a+n);
    m = a[0];
    for(i=0; i<n-1; i++){
        if(a[i+1]-m <= 1)
            count++;
        else{
            if(max < count)
                max = count;
            count = 1;
            m = a[i+1];
        }
    }
    if(max < count)
        max = count;
    cout << max;
    return 0;
}