#include <cstdio>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <cctype>
#include <utility>
#include <queue>
#include <cmath>
#include <complex>
using namespace std;

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPII;
typedef pair<LL, LL> PLL;
typedef pair<int, LL> PIL;
typedef pair<LL, int> PLI;
typedef double DB;

#define pb push_back
#define mset(a, b) memset(a, b, sizeof a)
#define all(x) (x).begin(), (x).end()
#define bit(x) (1 << (x))
#define bitl(x) (1LL << (x))
#define sqr(x) ((x) * (x))
#define sz(x) ((int)(x.size()))
#define counti(x) (__builtin_popcount(x))
#define countl(x) (__builtin_popcountll(x))
#define clz(x) (__builtin_clz(x))
#define clzl(x) (__builtin_clzll(x))
#define ctz(x) (__builtin_ctz(x))
#define ctzl(x) (__builtin_ctzll(x))

#define rep(i, n) for (int (i) = 0; (i) < (int)(n); ++(i))

#define X first
#define Y second

#define Error(x) cout << #x << " = " << x << endl

template <typename T, typename U> 
inline void chkmax(T& x, U y) {
    if (x < y) x = y;
}

template <typename T, typename U>
inline void chkmin(T& x, U y) {
    if (y < x) x = y;
}

const int MN = 300005;
int n, m, T, cnt;
VI con[MN];
int a[MN], b[MN], w[MN];
int vis[MN];

void dfs(int u) {
  cnt++;
  vis[u] = T;
  for (int i = 0; i < con[u].size(); i++) {
    int v = con[u][i];
    if (vis[v] == T) continue;
    dfs(v);
  }
}

bool tree() {
  T++;
  cnt = 0;
  dfs(0);
  return cnt == n;
}

int main() {

  int tn;
  for (cin >> tn; tn--; ) {
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; i++) {
      con[i].clear();
    }
    for (int i = 0; i < m; i++) {
      scanf("%d%d%d", a + i, b + i, w + i);
      a[i]--, b[i]--;
      con[a[i]].push_back(b[i]);
      con[b[i]].push_back(a[i]);
    }
    if (!tree()) {
      puts("0");
      continue;
    }
    int mask = 0;
    for (int i = 0; i >= 0; i--) {
      mask += bit(i);
      for (int j = 0; j < n; j++) con[j].clear();
      for (int j = 0; j < m; j++) {
        if ((mask & w[j]) == mask) {
          int u = a[j];
          int v = b[j];
          con[u].push_back(v);
          con[v].push_back(u);
        }
      }
      if (!tree()) {
        mask -= bit(i); 
      }
    }
    printf("%d\n", mask);
  }

  return 0;
}