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

const int N = 2e6 + 10;

int n, tot;
int a[N], st[N], b[N];
map<int, int> M;

bool check(int len) {
    for (int i = 1; i <= tot; i++) {
        b[i] = st[i] - st[i - 1];
    }
    for (int i = 1; i <= tot; i++) {
        if (st[i] > st[i - 1]) {
            if (i + len - 1 > tot) return false;
            int d = st[i] - st[i - 1];
            b[i] -= d, b[i + len] += d;
        }
    }
    for (int i = 1; i <= tot; i++) {
        b[i] += b[i - 1];
        if (b[i] < 0) return false;
    }
    return true;
}

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    sort(a + 1, a + 1 + n);
    a[0] = 1e9 + 7;
    for (int i = 1; i <= n; i++) {
        if (a[i] != a[i - 1]) {
            tot++;
            if (a[i] - a[i - 1] > 1) tot++;
            M[a[i]] = tot;
        }
        st[M[a[i]]]++;
    }

    int l = 1, r = tot;
    while (l < r) {
        int mid = l + r + 1 >> 1;
        if (check(mid)) l = mid;
        else r = mid - 1;
    }
    cout << l << endl;

    return 0;
}