#include <bits/stdc++.h>

#define forn(i, n) for (int i = 0; i < n; i++)
#define re return
#define pb push_back
#define all(a) a.begin(), a.end()
#define sz(a) (int)a.size()
#define x first
#define y second
#define point pair <int, int>
#define re return
#define se second
#define fi first
#define mp(a, b) make_pair(a, b)
#define mp1(a, b, c, d) make_pair(mp(a, b), mp(c, d))
using namespace std;
typedef long long ll;

int ans, n;
vector<int> a;
int main() {
    iostream::sync_with_stdio(0);
    //freopen("a.in", "r", stdin);
    cin >> n;;
    a.resize(n);
    forn (i, n) {
        cin >> a[i];
    }
    sort(a.begin(), a.end());
    int j = 0;
    forn (i, n) {
        while (j < sz(a) && a[j] - a[i] <= 1)
            j++;
        ans = max(ans, j - i);
    }
    cout << ans;
    return 0;
}