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

bool check(vector<int> &count, int N, int mid)
{
    if (count[N] < mid)
        return false;

    int uni = 0;
    int flag = 0;
    for (int i = 0; i <= N; i++)
    {
        if (count[i])
        {
            uni++;
        }
    }

    if (count[N] == mid)
    {
        uni--;
    }

    return uni >= mid;
}

int findOptimalSize(int N, vector<int> &A)
{

    vector<int> count(N + 1);
    for (int i = 0; i < N; i++)
    {
        count[A[i]]++;
    }
    if (N == 1)
    {
        return 0;
    }
    sort(count.begin(), count.end());

    int start = 1;
    int end = N;
    int ans = 0;
    while (start <= end)
    {
        int mid = (start + end) / 2;
        if (check(count, N, mid))
        {
            ans = mid;
            start = mid + 1;
        }
        else
        {
            end = mid - 1;
        }
    }

    return ans;
}

int main()
{

    int N;
    cin >> N;

    vector<int> A(N);
    for (int i = 0; i < N; i++)
    {
        cin >> A[i];
    }

    cout << findOptimalSize(N, A) << endl;
}