#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define repd(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define vi vector<int>
#define vpii vector<pii>
#define sz(x) ((int)(x.size()))
#define fi first
#define se second
#define ll long long int
#define mod 1000000007
int a[110];
int main() 
{         
    int i,n,j;
    cin>>n;
    rep(i,1,n)
    {
        cin>>a[i];
    }
    int an=0,m=0;
    rep(i,0,100)
    {
        an=0;
        rep(j,1,n)
        {
            if(i-a[j]<=1&&i-a[j]>=0)
            an++;
        }
        m=max(an,m);
    }
    cout<<m;
    return 0;
}