#include <bits/stdc++.h>
using namespace std;
using ll = long long;
template <class t, class u>
void chmax(t& first, u second) {
  if (first < second) first = second;
}
template <class t, class u>
void chmin(t& first, u second) {
  if (second < first) first = second;
}
template <class t>
using vc = vector<t>;
template <class t>
using vvc = vc<vc<t>>;
using pi = pair<int, int>;
using vi = vc<int>;
template <class t, class u>
ostream& operator<<(ostream& os, const pair<t, u>& p) {
  return os << "{" << p.first << "," << p.second << "}";
}
template <class t>
ostream& operator<<(ostream& os, const vc<t>& v) {
  os << "{";
  for (auto e : v) os << e << ",";
  return os << "}";
}
using uint = unsigned;
using ull = unsigned long long;
template <class t, size_t n>
ostream& operator<<(ostream& os, const array<t, n>& first) {
  return os << vc<t>(first.begin(), first.end());
}
template <int i, class T>
void print_tuple(ostream&, const T&) {}
template <int i, class T, class H, class... Args>
void print_tuple(ostream& os, const T& t) {
  if (i) os << ",";
  os << get<i>(t);
  print_tuple<i + 1, T, Args...>(os, t);
}
template <class... Args>
ostream& operator<<(ostream& os, const tuple<Args...>& t) {
  os << "{";
  print_tuple<0, tuple<Args...>, Args...>(os, t);
  return os << "}";
}
template <class t>
void print(t x, int suc = 1) {
  cout << x;
  if (suc == 1) cout << "\n";
  if (suc == 2) cout << " ";
}
ll read() {
  ll i;
  cin >> i;
  return i;
}
vi readvi(int n, int off = 0) {
  vi v(n);
  for (int i = int(0); i < int(n); i++) v[i] = read() + off;
  return v;
}
pi readpi(int off = 0) {
  int first, second;
  cin >> first >> second;
  return pi(first + off, second + off);
}
template <class T>
void print(const vector<T>& v, int suc = 1) {
  for (int i = int(0); i < int(v.size()); i++)
    print(v[i], i == int(v.size()) - 1 ? suc : 2);
}
string readString() {
  string s;
  cin >> s;
  return s;
}
template <class T>
T sq(const T& t) {
  return t * t;
}
void yes(bool ex = true) {
  cout << "Yes"
       << "\n";
  if (ex) exit(0);
}
void no(bool ex = true) {
  cout << "No"
       << "\n";
  if (ex) exit(0);
}
void possible(bool ex = true) {
  cout << "Possible"
       << "\n";
  if (ex) exit(0);
}
void impossible(bool ex = true) {
  cout << "Impossible"
       << "\n";
  if (ex) exit(0);
}
constexpr ll ten(int n) { return n == 0 ? 1 : ten(n - 1) * 10; }
const ll infLL = LLONG_MAX / 3;
const int inf = INT_MAX / 2 - 100;
int topbit(signed t) { return t == 0 ? -1 : 31 - __builtin_clz(t); }
int topbit(ll t) { return t == 0 ? -1 : 63 - __builtin_clzll(t); }
int botbit(signed first) { return first == 0 ? 32 : __builtin_ctz(first); }
int botbit(ll first) { return first == 0 ? 64 : __builtin_ctzll(first); }
int popcount(signed t) { return __builtin_popcount(t); }
int popcount(ll t) { return __builtin_popcountll(t); }
bool ispow2(int i) { return i && (i & -i) == i; }
ll mask(int i) { return (ll(1) << i) - 1; }
bool inc(int first, int second, int c) {
  return first <= second && second <= c;
}
template <class t>
void mkuni(vc<t>& v) {
  sort(v.begin(), v.end());
  v.erase(unique(v.begin(), v.end()), v.end());
}
ll rand_int(ll l, ll r) {
  static mt19937_64 gen(chrono::steady_clock::now().time_since_epoch().count());
  return uniform_int_distribution<ll>(l, r)(gen);
}
template <class t>
void myshuffle(vc<t>& first) {
  for (int i = int(0); i < int(int(first.size())); i++)
    swap(first[i], first[rand_int(0, i)]);
}
template <class t>
int lwb(const vc<t>& v, const t& first) {
  return lower_bound(v.begin(), v.end(), first) - v.begin();
}
vvc<int> readGraph(int n, int m) {
  vvc<int> g(n);
  for (int i = int(0); i < int(m); i++) {
    int first, second;
    cin >> first >> second;
    first--;
    second--;
    g[first].push_back(second);
    g[second].push_back(first);
  }
  return g;
}
vvc<int> readTree(int n) { return readGraph(n, n - 1); }
template <class E>
struct bipartitematching {
  int n, m;
  vvc<E> g;
  vi dist, vis;
  vi to, ot;
  int sz;
  bipartitematching(int nn, int mm)
      : n(nn), m(mm), g(n), dist(n), vis(n), to(n, -1), ot(m, -1), sz(0) {}
  void ae(int first, E e) { g[first].push_back(e); }
  void bfs() {
    fill(dist.begin(), dist.end(), -1);
    vi q;
    int h = 0;
    auto rc = [&](int v, int d) {
      if (v == -1 || dist[v] != -1) return;
      dist[v] = d;
      q.push_back(v);
    };
    for (int i = int(0); i < int(n); i++)
      if (to[i] == -1) rc(i, 0);
    while (h < (int)q.size()) {
      int v = q[h++];
      for (auto e : g[v]) rc(ot[e], dist[v] + 1);
    }
  }
  bool dfs(int v) {
    if (vis[v]) return 0;
    vis[v] = 1;
    for (auto e : g[v]) {
      if (ot[e] == -1 || (dist[v] + 1 == dist[ot[e]] && dfs(ot[e]))) {
        to[v] = e;
        ot[e] = v;
        return 1;
      }
    }
    return 0;
  }
  void calc() {
    while (1) {
      bfs();
      fill(vis.begin(), vis.end(), 0);
      int f = 0;
      for (int i = int(0); i < int(n); i++)
        if (to[i] == -1)
          if (dfs(i)) f++;
      if (f == 0) break;
      sz += f;
    }
  }
};
signed main() {
  cin.tie(0);
  ios::sync_with_stdio(0);
  cout << fixed << setprecision(20);
  using T = tuple<int, int, int>;
  int n, m;
  cin >> n >> m;
  vc<T> es;
  for (int i = int(0); i < int(m); i++) {
    int first, second, c;
    cin >> first >> second >> c;
    first--;
    second--;
    es.emplace_back(c, first, second);
  }
  sort(es.begin(), es.end());
  int lw = 0, up = m + 1;
  while (up - lw > 1) {
    int mid = (lw + up) / 2;
    bipartitematching<int> bm(n, n);
    for (int i = int(0); i < int(mid); i++) {
      int c, first, second;
      tie(c, first, second) = es[i];
      bm.ae(first, second);
    }
    bm.calc();
    if (bm.sz == n)
      up = mid;
    else
      lw = mid;
  }
  int ans = -1;
  if (lw < m) ans = get<0>(es[lw]);
  print(ans);
}
