ABC408E AC

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#ifndef __DEBUG__
#define dbg(...) 42
#endif
template <class T>
using mpq = priority_queue<T, vector<T>, greater<T>>;

namespace rngs = std::ranges;
using ll = long long;
using a2l = array<ll, 2>;
using pll = pair<ll, ll>;
using vl = vector<ll>;

void solve() {
    ll n, m;
    cin >> n >> m;
    vector<vector<a2l>> g(n + 1);
    for (ll i = 0, u, v, w; i < m; ++i) {
        cin >> u >> v >> w;
        g[u].push_back({v, w}), g[v].push_back({u, w});
    }

    auto check_bit = [&](ll bit) -> bool {
        vl vis(n + 1);
        queue<ll> q;
        q.push(1);
        while (!q.empty()) {
            auto u = q.front();
            q.pop();
            if (vis[u])
                continue;
            vis[u] = 1;
            for (auto [v, w] : g[u]) {
                if (!vis[v] && ((w | bit) == bit)) {
                    q.push(v);
                }
            }
        }
        return vis[n] == 1;
    };

    ll ans = (1ll << 32) - 1;
    for (ll i = 31; i >= 0; --i) {
        if (check_bit(ans ^ (1ll << i)))
            ans ^= (1ll << i);
    }
    cout << ans << '\n';
}

int main(int argc, char **argv) {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    solve();

    return 0;
};