#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;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0;a_i < n;a_i++){
       cin >> a[a_i];
    }
    
    std::sort(a.begin(), a.end());
    vector<int> a_c(n,1);
    int max = 0;
    for (int i = a.size() -1; i >=0; i--) {
        for (int j = i -1; j >=0; j--) {
            if (abs(a[i] - a[j]) <= 1) {
                a_c[i] = a_c[i] + 1;
            } else {
                break;
            } 
            
        }
        
        if (max < a_c[i]) {
            max = a_c[i];
        }
        
    }
    
    cout<<max<<endl;
    return 0;
}