#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];
    }
    
    int max = 0, neg, pos, zer;
    for(int i=0; i<n-1; i++){
        neg = 0; pos = 0; zer = 0;
        for(int j = 0; j<n; j++){
            if(j == i)
                continue;
            
            if(abs(a[i]-a[j]) <= 1){
                if(a[i]-a[j] > 0) pos++;
                else if(a[i]-a[j] < 0) neg++;
                else zer++;
            }
        }
                
        if(max < (pos+zer))
            max = pos+zer;

        if(max < (neg+zer))
            max = neg+zer;
    }
        
    if(max == 0) cout << max << endl;
    else cout << max+1 << endl;
    return 0;
}