import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        Integer[] a = new Integer[n];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        List<Integer> as = Arrays.asList(a);
        System.out.println(as.stream().map(i -> takeForChoice(i, as)).max((x,y) -> x > y ? 1 : -1).get());
    }
    

    public static int takeForChoice(int i, List<Integer> is) {
        int cInf = 0;
        int cSup = 0;
        for(Integer in : is) {
            if(i==in) {
                cInf ++;
                cSup ++;
            } else if(i > in && i - in == 1) {
                cInf ++;
            } else if(in > i && in - i == 1) {
                cSup ++;
            }
        }
        return cInf > cSup ? cInf : cSup;
    }
}