#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int size;
    int temp;
    int max = 0;
    int current_m = 0;
    int current_p = 0;
    int current = 0;
    int curn = 0;
    vector<int> input;
    cin >> size;
    for(int i = 0; i < size; ++i) {
        cin >> temp;
        input.push_back(temp);
    }
    for(int i = 0; i < size; ++i) {
        curn = input[i];
        current_m = 1;
        current_p = 1;
        for(int j = 0; j < size; ++j) {
            if(i == j) continue;
            if(curn == input[j]) {
                current_m++;
                current_p++;
            } else if(curn - 1 == input[j]) {
                current_m++;
            } else if(curn + 1 == input[j]) {
                current_p++;
            }
        }
        current = current_m > current_p ? current_m : current_p;
        if (current > max) max = current;
    }
    cout << max;
    return 0;
}