#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 m = INT_MIN,max1 = INT_MIN;
    int c = 0,c1 = 0;
    
    for(int i = 0; i < n; i++)
        {
        c = 0;
        c1 = 0;
        for(int j  = i+1; j < n; j++)
            {
            if(a[i]-a[j] == 1 || a[i]-a[j] == 0)
                {
                c++;
            }
            if(c > m)
                m = c;
            if(a[i]-a[j] == -1 || a[i]-a[j] == 0)
                {
                c1++;
            }
            if(c1 > max1)
                max1 = c1;
        }
    }
    cout << max(m,max1) + 1 <<endl;
    
    return 0;
}