#include <iostream>
#include <cstdio>
#include <string.h>
#include <algorithm>
#include <vector>
#include <string>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <sstream>
#include <cmath>
#include <ctime>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector< vector<int> > vvi;
typedef vector<ll> vl;
typedef vector< vector<ll> > vvl;

#define forn(i, n) for (int i = 0; i < (int)(n); i++)
#define forv(i, v) forn(i, v.size())
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back

int main() {
#ifdef NEREVAR_PROJECT
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    int n; cin >> n;
    vi a(n);
    forn(i, n) cin >> a[i];
    sort(all(a));
    int ans = 0;
    forn(l, n) {
        int r = l;
        while (r < n && a[r] - a[l] <= 1) r++;
        ans = max(ans, r - l);
    }
    cout << ans << endl;
    return 0;
}