#include <iostream>
#include <stdio.h>
#include <algorithm>

using namespace std;

const int N=1010;
int a[N];
int n,ans;

int main(){
    //freopen("task.inp","r",stdin);
    //freopen("task.out","w",stdout);
    scanf("%d",&n);
    for(int i=0;i<n;i++) scanf("%d",&a[i]);
    sort(a,a+n);
    int ans=0;
    for(int i=0;i<n;i++)
        for(int j=i;j<n;j++)
            if(a[j]-a[i]<=1) ans=max(ans,j-i+1);
    cout<<ans<<endl;
}