#include<bits/stdc++.h>

using namespace std;
int max1(int a,int b){
    if(a>=b)
        return a;
    return b;
}

int main(){
    int n;
    cin >> n;
    vector<int> a(n);
    for(int a_i = 0;a_i < n;a_i++){
       cin >> a[a_i];
    }
    int save=0,count0=0,count1=0,count_1=0;
    int sum1,sum2,sum3,sum;
    for(int i=0;i<n;i++){
        count0=1;count1=0;count_1=0;
        for(int j=0;j<n;j++){
            if(a[i]-a[j]==0 &&j!=i){
                count0++;
            }
            if(a[i]-a[j]==1 &&j!=i){
                count1++;
            }
            if(a[i]-a[j]==-1 &&j!=i){
                count_1++;
            }
        }
        sum1=count0+count1;sum2=count0+count_1;
        sum=max1(sum1,sum2);
        if(sum>save){
            save=sum;
        }
    }
    cout<<save;
    return 0;
}