#include<bits/stdc++.h>
using namespace std;
#define endl "\n"
#define int long long
#define faster() ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
#define mod 1000000007
#define maxN 10005
 
void solve(){
    int n, l;
    cin >> n >> l;
    int x;
    int freq[l][2] = {}; // Tần suất bit 0 và 1 ở mỗi vị trí
    for (int i = 0; i < n; ++i) {
        cin >> x;
        for (int j = 0; j < l; ++j) {
            int bit = (x >> j) & 1; // Lấy bit thứ j trong x
            freq[j][bit] += 1;
        }
    }
 
    int y = 0;
    for (int j = 0; j < l; ++j) {
        if (freq[j][1] > freq[j][0]) // Bit 1 xuất hiện nhiều hơn ở vị trí j
            y |= (1 << j); // Đặt bit j của y thành 1
    }
    cout << y << endl;
}
 
signed main(){
    faster();
    int test = 1 ;
    cin >> test;
    while(test--){
        solve();
    }
}

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7
3 5
18 9 21
3 5
18 18 18
1 1
1
5 30
1 2 3 4 5
6 10
99 35 85 46 78 55
2 1
0 1
8 8
5 16 42 15 83 65 78 42