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

public class Solution {

        private static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }
    }

    public static void main(String args[]) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        solve(in, out);
        out.close();
    }

    private static void solve(InputReader in, PrintWriter out) {
        int N = in.nextInt();
        int a[] = new int[N];
        for (int i = 0; i < N; i++) {
            int x = in.nextInt();
            a[i] = x;
        }
        Arrays.sort(a);
        int answer = 0;
        int prev = 0;
        for (int i = 1; i < N; i++) {
            if (a[i] - a[prev] > 1) {
                answer = Math.max(i - prev, answer);
                prev = i;
            }
        }
        answer = Math.max(answer, N - prev);
        out.println(answer);
    }
}