#include <bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
const int inf = 0x3f3f3f3f;
const long long INF = 0x3f3f3f3f3f3f3f3fLL;
const double PI = acos(-1.0);
const long double eps = 1e-8;
const int mod = 998244353;
const int maxn = 2e5 + 100;
const int N = 3e4 + 100;
const int M = 1e5 + 10;
const long long mm = (1LL << 32);
template <class T>
inline void read(T &x) {
  x = 0;
  char c = getchar();
  bool f = 0;
  for (; !isdigit(c); c = getchar()) f ^= c == '-';
  for (; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
  x = f ? -x : x;
}
template <class T>
inline void write(T x) {
  if (x < 0) {
    putchar('-');
    x = -x;
  }
  T y = 1;
  int len = 1;
  for (; y <= x / 10; y *= 10) ++len;
  for (; len; --len, x %= y, y /= 10) putchar(x / y + 48);
}
long long qpow(long long a, long long b, long long mod) {
  long long ans = 1;
  while (b) {
    if (b & 1) ans = (ans * a) % mod;
    b >>= 1;
    a = (a * a) % mod;
  }
  return ans;
}
struct Edge {
  int from, to;
  long long cap, flow;
  Edge(int u, int v, long long c, long long f)
      : from(u), to(v), cap(c), flow(f) {}
};
struct Dinic {
  int n, m, s, t;
  vector<Edge> edges;
  vector<int> G[N];
  bool vis[N];
  int d[N];
  int cur[N];
  void init(int n) {
    this->n = n;
    for (int i = 0; i < n; ++i) G[i].clear();
    edges.clear();
  }
  void AddEdge(int from, int to, long long cap) {
    edges.push_back({from, to, cap, 0});
    edges.push_back({to, from, 0, 0});
    m = edges.size();
    G[from].push_back(m - 2);
    G[to].push_back(m - 1);
  }
  bool BFS() {
    memset(vis, 0, sizeof(vis));
    memset(d, 0, sizeof(d));
    queue<int> q;
    q.push(s);
    d[s] = 0;
    vis[s] = 1;
    while (!q.empty()) {
      int x = q.front();
      q.pop();
      for (int i = 0; i < G[x].size(); ++i) {
        Edge &e = edges[G[x][i]];
        if (!vis[e.to] && e.cap > e.flow) {
          vis[e.to] = true;
          d[e.to] = d[x] + 1;
          q.push(e.to);
        }
      }
    }
    return vis[t];
  }
  long long DFS(int x, long long a) {
    if (x == t || a == 0) return a;
    long long flow = 0, f;
    for (int &i = cur[x]; i < G[x].size(); ++i) {
      Edge &e = edges[G[x][i]];
      if (d[x] + 1 == d[e.to] && (f = DFS(e.to, min(a, e.cap - e.flow))) > 0) {
        e.flow += f;
        edges[G[x][i] ^ 1].flow -= f;
        flow += f;
        a -= f;
        if (a == 0) break;
      }
    }
    return flow;
  }
  long long Maxflow(int s, int t) {
    this->s = s, this->t = t;
    long long flow = 0;
    while (BFS()) {
      memset(cur, 0, sizeof(cur));
      flow += DFS(s, INF);
    }
    return flow;
  }
} mf;
int n, m;
int U[M], V[M], W[M];
bool check(int x) {
  mf.init(2 * n + 5);
  int S = 0, T = 2 * n + 1;
  for (int i = 1; i <= n; ++i) mf.AddEdge(S, i, 1);
  for (int i = 1; i <= n; ++i) mf.AddEdge(n + i, T, 1);
  for (int i = 1; i <= m; ++i) {
    int u = U[i], v = V[i], w = W[i];
    if (w <= x) {
      mf.AddEdge(u, v + n, 1);
    }
  }
  return mf.Maxflow(S, T) == (long long)n;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  for (int i = 1; i <= m; ++i) {
    cin >> U[i] >> V[i] >> W[i];
  }
  int l = 1, r = 1e9, ans = -1;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if (check(mid))
      ans = mid, r = mid - 1;
    else
      l = mid + 1;
  }
  cout << ans << "\n";
  return 0;
}
