#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];
    }
    
    vector<int> table(101,0);
    for (int i = 0; i < n; ++i) 
        ++table[a[i]];
    
    int maxCount = 0;
    for (int i = 1; i < 100; ++i) {
        maxCount = max(maxCount, table[i] + table[i+1]);     
    }
    cout << maxCount;
    return 0;
}