#include<bits/stdc++.h>
using namespace std;

#define pb push_back
#define ui unsigned int
#define ll long long
#define ull unsigned long long
#define rev(v) reverse(v.begin(),v.end())
#define FOR(a,b) for(int i = (a); i <= (b); ++i)
#define FORD(a,b) for(int i = (a); i >= (b); --i)
#define rev(v) reverse(v.begin(),v.end())
#define sort3(ARR,n) sort(ARR,ARR+n,less<long int>())
#define sort4(ARR,n) sort(ARR,ARR+n,greater<long int>())
#define asort(v) sort(v.begin(),v.end(),less<long int>())
#define desort(v) sort(v.begin(),v.end(),greater<long int>())
#define display(shaan) for (std::vector<int>::const_iterator i = shaan.begin(); i != shaan.end(); ++i) std::cout << *i << ' ';
#define fastScan ios_base::sync_with_stdio(0); cin.tie(NULL);
#define sz(v) (int)v.size();

vector< vector<int> >v;

int main()
{
    fastScan;
    int n;
    cin>>n;
    int arr[n];
    FOR(0,n-1){
        cin>>arr[i];
    }
    sort3(arr,n);
    int st,st1,ans=2,flag;
    st=0;st1=1;
    flag=0;
    FOR(0,n-2){
        if(arr[st1]-arr[st]<=1){
            st1=i+1;
            ans=max(ans,(st1-st));
            if(st1==n-1)
            flag=12;
            continue;
        }
        st=i;
        st1=i+1;
    }
    //cout<<"ST="<<st<<" and ST1 = "<<st1<<endl;
    
    if(arr[n-1]-arr[0]<=1)
    ans++;
    cout<<ans;

    return 0;
}
//yo freaker, don't be a tatti seeker :P

// sys/resource rlimit l limit search