import java.io.*;
import java.util.*;
public class TestClass {
	
	public static void main (String args[]) {
		BufferedReader br = new BufferedReader( new InputStreamReader ( System.in ));
		try {
			int n = Integer.parseInt(br.readLine());
			int arr[] = new int[102];
			for ( int i = 0 ; i <  arr.length ; i++  ){
				arr[i] = 0;
			}
			//int x ;
			String[] arrStrings = br.readLine().split(" ");
			for ( int i = 0 ; i < n ; i++ ){
				arr[Integer.parseInt(arrStrings[i])] += 1; 
			}
			//for ( int i = 0 ; i < arr.length ; i++)
			//	System.out.print(arr[i]+" ");		
			Integer[] newArr = new Integer[101];
			for ( int i = 0 ; i < arr.length-1 ; i++ ){
				newArr[i] = arr[i] + arr[i+1];
			}
			List<Integer> newArrLst = Arrays.asList(newArr);
			//System.out.println();
			//for ( Integer i : newArrLst ) System.out.print(i);
			Integer y = Collections.max(newArrLst);
			//System.out.println("---------------------------");
			System.out.println(y);
		}
		catch ( Exception e ){
			e.printStackTrace();
		}
		int x = 0 ;
		
	}
}