#include <bits/stdc++.h>
using namespace std;
set<long long int> st;
set<long long int>::iterator it;
long long int cnt[200010];
int main() {
  long long int n, a, b, x, y, z, p, m, d, mn, mx, t, i;
  scanf("%lld", &t);
  while (t--) {
    scanf("%lld", &n);
    p = 0;
    for (i = 1; i <= n; i++) {
      scanf("%lld", &a);
      st.insert(a);
      cnt[a]++;
      p = max(p, cnt[a]);
    }
    x = st.size();
    if (x == 1) {
      if (p >= 2) {
        cout << 1 << endl;
      } else
        cout << 0 << endl;
    } else {
      x = x - 1;
      if (p <= x)
        cout << p << endl;
      else {
        d = p - x;
        if (d > 1)
          cout << x + 1 << endl;
        else
          cout << x << endl;
      }
    }
    for (i = 1; i <= n; i++) cnt[i] = 0;
    st.clear();
  }
  return 0;
}
