#include<stdio.h>
void merge(int a[],int i1,int j1,int i2,int j2)
{
    int temp[100006];    //array used for merging
    int i,j,k;
    i=i1;    //beginning of the first list
    j=i2;    //beginning of the second list
    k=0;

    while(i<=j1 && j<=j2)    //while elements in both lists
    {
        if(a[i]<a[j])
            temp[k++]=a[i++];
        else
            temp[k++]=a[j++];
    }

    while(i<=j1)    //copy remaining elements of the first list
        temp[k++]=a[i++];

    while(j<=j2)    //copy remaining elements of the second list
        temp[k++]=a[j++];

    for(i=i1,j=0;i<=j2;i++,j++)
        a[i]=temp[j];
}
void mergesort(int a[],int i,int j)
{
    int mid;

    if(i<j)
    {
        mid=(i+j)/2;
        mergesort(a,i,mid);        //left recursion
        mergesort(a,mid+1,j);    //right recursion
        merge(a,i,mid,mid+1,j);    //merging of two sorted sub-arrays
    }
}
int main(){
	int i,j,n,p,c,maximum;
	scanf("%d",&n);
	int arr[n],max[n],k;
	for(i=0;i<n;i++){
		scanf("%d",&arr[i]);
	}
	 mergesort(arr,0,n-1);
	 for(i=0;i<n-1;i++){
	 	max[i]=1;
	 	for(j=i+1;j<n;j++){
	 		p=arr[j]-arr[i];
	 		if(p<=1&&p>=0){
	 		max[i]++;
			 }
			 else if(p>1){
			 	break;
			 }
	 		
		 }
	 	
	 }
	 max[n-1]=1;
	// for(i=0;i<n;i++){
	// 	printf("%d--",max[i]);
	// }
	  maximum = max[0];
 
  for (c = 1; c <n; c++)
  {
    if (max[c] > maximum)
    {
       maximum  = max[c];
    }
  }
  printf("%d\n",maximum);
	
	return 0;
	
}