/* Problem URL: https://codeforces.com/problemset/problem/2117/G */

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template <class T, class comp = less<>>
using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (int i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

const int oo = INT32_MAX >> 1;
const ll OO = INT64_MAX >> 1;


void pre()
{

}

#define TEST 1

void solve()
{
    int n, m;
    cin >> n >> m;

    V<tuple<ll, int, int>> edges(m);
    for (auto &[c, u, v] : edges) {
        cin >> u >> v >> c;
        u--, v--;
    }

    sortv(edges);

    vi dsu(n);
    rep(i, n) {
        dsu[i] = i;
    }

    function<int(int)> find_p = [&](int i) {
        if (dsu[i] == i) {
            return i;
        }
        return dsu[i] = find_p(dsu[i]);
    };

    auto join = [&](int a, int b) {
        a = find_p(a);
        b = find_p(b);
        dsu[b] = a;
        return a != b;
    };

    V<V<pair<int, ll>>> graph(n);

    for (auto [c, u, v] : edges) {
        if (join(u, v)) {
            graph[u].emplace_back(v, c);
            graph[v].emplace_back(u, c);
        }
    }

    V<pair<ll, ll>> every;
    every.reserve(n);
    ll mians = OO;
    ll maans = 0;

    function<void(int, int, ll, ll)> dfs = [&](int i, int p, ll mi, ll ma) {
        if (i == n - 1) {
            mians = mi;
            maans = ma;
        }

        every.emplace_back(mi, ma);

        for (auto [j, c] : graph[i]) {
            if (j == p) {
                continue;
            }

            dfs(j, i, min(mi, c), max(ma, c));
        }
    };

    dfs(0, 0, OO, 0);
    
    ll ans = OO;

    for (auto [mi, ma] : every) {
        rmin(ans, min(mians, mi) + max(maans, ma));
    }

    cout << ans << '\n';
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    pre();

    int t;
    (TEST && cin >> t) || (t = 1);
    while (t--) {
        solve();
    }
}