#include <bits/stdc++.h>
using namespace std;
class matching {
 public:
  vector<vector<long long>> g;
  vector<long long> pa;
  vector<long long> pb;
  vector<long long> was;
  long long n, m;
  long long res;
  long long iter;
  matching(long long _n, long long _m) : n(_n), m(_m) {
    assert(0 <= n && 0 <= m);
    pa = vector<long long>(n, -1);
    pb = vector<long long>(m, -1);
    was = vector<long long>(n, 0);
    g.resize(n);
    res = 0;
    iter = 0;
  }
  void add(long long from, long long to) {
    assert(0 <= from && from < n && 0 <= to && to < m);
    g[from].push_back(to);
  }
  bool dfs(long long v) {
    was[v] = iter;
    for (long long u : g[v]) {
      if (pb[u] == -1) {
        pa[v] = u;
        pb[u] = v;
        return true;
      }
    }
    for (long long u : g[v]) {
      if (was[pb[u]] != iter && dfs(pb[u])) {
        pa[v] = u;
        pb[u] = v;
        return true;
      }
    }
    return false;
  }
  long long solve() {
    while (true) {
      iter++;
      long long add = 0;
      for (long long i = 0; i < n; i++) {
        if (pa[i] == -1 && dfs(i)) {
          add++;
        }
      }
      if (add == 0) {
        break;
      }
      res += add;
    }
    return res;
  }
  long long run_one(long long v) {
    if (pa[v] != -1) {
      return 0;
    }
    iter++;
    return (long long)dfs(v);
  }
};
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  long long n, m;
  cin >> n >> m;
  vector<array<long long, 3>> a;
  for (long long i = 0; i < m; i++) {
    long long u, v, d;
    cin >> u >> v >> d;
    a.push_back({d, u, v});
  }
  sort(a.begin(), a.end());
  auto check = [&](long long mid) {
    matching mat(n, n);
    for (long long i = 0; i <= mid; i++) mat.add(a[i][1] - 1, a[i][2] - 1);
    return (mat.solve() == n);
  };
  long long l = n - 1, r = m - 1, ans = -1;
  while (l <= r) {
    long long mid = (l + r) / 2;
    if (check(mid)) {
      ans = a[mid][0];
      r = mid - 1;
    } else
      l = mid + 1;
  }
  cout << ans << '\n';
}
