#include <bits/stdc++.h>
#define int int64_t

using namespace std;

int32_t main()
{
    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        int a [n];
        for (auto &i: a)
            cin >> i;
        if (n == 1)
        {
            cout << "0\n";
            continue;
        }
        map <int, int> cnt;
        for (auto i: a)
            cnt [i]++;
        int ans = LLONG_MIN;
        for (auto i: cnt)
        {
            int now;
            if (i.second > cnt.size())
                now = cnt.size();
            else
                now = min(i.second, (int)cnt.size() - 1);
            ans = max(now, ans);
        }
        cout << ans << "\n";
    }
}