// Code by Heratino & Nelofus
// Narcissus & どうか安寧な記憶を

#include <bits/stdc++.h>
using i64 = long long;

//{{{誰にもなれない 私 胸張ってさ
template<typename Ta, typename Tb>
inline void chkmax(Ta &a, const Tb &b) {if (a < b)	a = b;}
template<typename Ta, typename Tb>
inline void chkmin(Ta &a, const Tb &b) {if (a > b)	a = b;}
char buf[1 << 20], *P1, *P2;
inline char gc() {
	if (P1 == P2)
		P2 = (P1 = buf) + fread(buf, 1, 1 << 20, stdin);
	return P1 == P2 ? EOF : *P1++;
}
template<typename T>
inline void read(T &ans) {
	ans = 0;
	T w = 1;
	char c = gc();
	while (!isdigit(c)) {
		if (c == '-')	w = -1;
		c = gc();
	}
	while (isdigit(c)) {
		ans = (ans << 3) + (ans << 1) + (c ^ 48);
		c = gc();
	}
	ans *= w;
}
template<typename T, typename ...Ts>
void read(T &a, Ts&... other) {
	read(a);
	read(other...);
}
//}}}

void solve() {
	int n;
	read(n);
	std::vector<int> app(n, 0);
	int mx = 0, nx = 0;
	for (int i = 0; i < n; i++) {
		int x;
		read(x);
		app[x - 1]++;
		int t = app[x - 1];
		if (t > mx)
			nx = mx, mx = t;
		else if (t > nx)
			nx = t;
	}
	int answer = mx | nx | ((mx & nx) ? (1 << std::__lg(mx & nx)) - 1 : 0);
	std::cout << answer << '\n';
}

int main() {
#ifdef HeratinoNelofus
	freopen("input.txt", "r", stdin);
#endif

	int T;
	read(T);
	while (T--) {
		solve();
	}
	return 0;
}