#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mkp make_pair
#define pb push_back
typedef pair <int, int> pii;

inline int read() {
    int x = 0, f = 0;
    char c = getchar();
    while (!isdigit(c)) {if (c == '-') f = 1; c = getchar();}
    while (isdigit(c)) x = (x << 1) + (x << 3) + (c & 15), c = getchar();
    return f? -x : x;
}

const int MAXN = 1e5;
int c[MAXN + 10], sum[MAXN + 10];

inline bool cmp(const int &x, const int &y) {return x > y;}
int main() {
    int T = read();
    while (T--) {
        int n = read();
        for (int i = 1; i <= n; ++i) {
            c[i] = read();
            ++sum[c[i]];
        }
        sort(sum + 1, sum + n + 1, cmp);
        int x = sum[1], y = sum[2], ans = 0;
    //    cerr << x << " " << y << endl;
        for (int i = 19; i >= 0; --i) {
            int j = 1 << i;
            int o1 = x & j;
            int o2 = y & j;
            if (!o1 && !o2) continue;
            if (o1 && o2) {
                ans |= (1 << i + 1) - 1;
            }
            else ans |= (1 << i);
        }
        printf("%d\n", ans);
    }
    return 0;
}