import java.util.*;
	import java.io.*;
	import java.math.*;
	public class Main {
		public static long mod= (long) (1e9 +7);
		static long sum=0;
		static long count=0;
		public static void main(String args[])
		{
			InputReader s= new InputReader(System.in);
			OutputStream outputStream= System.out;
			PrintWriter out= new PrintWriter(outputStream);
			int n= s.nextInt();
			int a[]= new int[n];
			for(int i=0;i<n;i++){
				a[i]= s.nextInt();
			}
			Arrays.sort(a);
			int cnt[]= new int[n];
			int j=1;
			for(int i=0;j<n;j++){
				if(a[j]-a[i]<=1){
					cnt[i]++;
				//	out.println(j);
				}
				else{
					i++;
					j=i;
				}
			}
			int max= Integer.MIN_VALUE;
			for(int i=0;i<n;i++){
				if(cnt[i]>max)
					max=cnt[i];
			}
				out.print(max+1);
			out.close();
		}
		
		static long combinations(long n,long r){   // O(r)
			if(r==0 || r==n) return 1;
			r= Math.min(r, n-r);
			long ans=n;  // nC1=n;
			for(int i=1;i<r;i++){
				ans= ans*(n-i);
				ans= ans/(i+1);
			}
			return ans;
			
		}
		static long modulo(long a,long b,long c) {
			long x=1;
			long y=a;
			while(b > 0){
				if(b%2 == 1){
					x=(x*y)%c;
				}
				y = (y*y)%c; // squaring the base
				b /= 2;
			}
			return  x%c;
		}
		static void catalan_numbers(int n) {
			long catalan[]= new long[n+1];
		    catalan[1] = 1;
		    for (int i = 2; i <= n; i++) {
		        for (int j = 1; j <= i - 1; j++) {
		            catalan[i] = catalan[i] + ((catalan[j]) * catalan[i - j]);
		        }
		    }
		}
		
		static ArrayList<Integer> primeFactors(int n)   // O(sqrt(n))
		{
		    // Print the number of 2s that divide n
			ArrayList<Integer> arr= new ArrayList<>();
		    while (n%2 == 0)
		    {
		        arr.add(2);
		        n = n/2;
		    }
		 
		    // n must be odd at this point.  So we can skip one element (Note i = i +2)
		    for (int i = 3; i <= Math.sqrt(n); i = i+2)
		    {
		        // While i divides n, print i and divide n
		        while (n%i == 0)
		        {
		            arr.add(i);
		            n = n/i;
		        }
		    }
		    // This condition is to handle the case when n is a prime number
		    // greater than 2
		    if (n > 2)
		        arr.add(n);
		    
		    return arr;
		}
	
		public static long expo(long a, long b){
			if (b==0)
		        return 1%mod;
		    if (b==1)
		        return a%mod;
		    if (b==2)
		        return ((a%mod)*(a%mod))%mod;
	
		    if (b%2==0){
		            return expo(expo(a%mod,(b%mod)/2)%mod,2%mod)%mod;
		    }
		    else{
		        return (a%mod)*(expo(expo(a%mod,(b-1)%mod/2)%mod,2%mod)%mod)%mod;
		    }
		}
		static class Pair implements Comparable<Pair>
		{
			long f;
			String s;
			Pair(long ii, String cc)
			{
				f=ii;
				s=cc;
			}
			
			public int compareTo(Pair o) 
			{
				return Long.compare(this.f, o.f);
			}
			
		}
		
		public static int[] sieve(int N){    // O(n*log(logn))
			int arr[]= new int[N+1];
			for(int i=2;i<Math.sqrt(N);i++){
				if(arr[i]==0){
					for(int j= i*i;j<= N;j= j+i){
						arr[j]=1;
					}
				}
			}
			return arr;
			// All the i for which arr[i]==0 are prime numbers.
		}
		static long gcd(long a,long b){       // O(logn)
			if(b==0) return a;
			return gcd(b,a%b);
		}
		static class InputReader {
	
		    public BufferedReader reader;
		    public StringTokenizer tokenizer;
	 
		    public InputReader(InputStream inputstream) {
		      reader = new BufferedReader(new InputStreamReader(inputstream));
		      tokenizer = null;
		    }
		    
		    public String nextLine(){
		    	String fullLine=null;
		    	while (tokenizer == null || !tokenizer.hasMoreTokens()) {
		            try {
		              fullLine=reader.readLine();
		            } catch (IOException e) {
		              throw new RuntimeException(e);
		            }
		            return fullLine;
		          }
		          return fullLine;
		    }
			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 long nextLong() {
			      return Long.parseLong(next());
			    }
		    public int nextInt() {
		      return Integer.parseInt(next());
		    }
		  }
	}