#include<iostream>
#include<algorithm>
using namespace std;

int main()
{
    int n;
    cin>>n;
    int a[n];
    for(int i = 0;i<n;i++)
        cin>>a[i];

    //int dp[n][n];
    int flag;
    int num,c = 1,maxc = 0;
    for(int i = 0;i<n;i++)
    {
        c = 1;
        for(int j = 0;j<n;j++)
        {
            if(i != j)
            {
                if((a[i] - a[j]) <= 1 && (a[i] - a[j])>=0)
                {
                    flag = 1;
                    num = a[j];
                    c++;
                }
            }
        }
        if(c>maxc)
            maxc = c;
    }

    cout<<maxc;

}