#include <bits/stdc++.h>
#pragma GCC optimize(2)
using namespace std;
const double eps = 1e-8;
const long long inf = 0x3f3f3f3f;
const double pi = acos(-1.0);
std::mt19937 rnd(233);
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}
long long tt;
namespace FastIO {
bool IOerror = 0;
inline char nc() {
  static char buf[100000], *p1 = buf + 100000, *pend = buf + 100000;
  if (p1 == pend) {
    p1 = buf;
    pend = buf + fread(buf, 1, 100000, stdin);
    if (pend == p1) {
      IOerror = 1;
      return -1;
    }
  }
  return *p1++;
}
inline bool blank(char ch) {
  return ch == ' ' || ch == '\n' || ch == '\r' || ch == '\t';
}
template <class T>
inline bool read(T& x) {
  bool sign = 0;
  char ch = nc();
  x = 0;
  for (; blank(ch); ch = nc())
    ;
  if (IOerror) return false;
  if (ch == '-') sign = 1, ch = nc();
  for (; ch >= '0' && ch <= '9'; ch = nc()) x = x * 10 + ch - '0';
  if (sign) x = -x;
  return true;
}
template <class T, class... U>
bool read(T& h, U&... t) {
  return read(h) && read(t...);
}
};  // namespace FastIO
inline long long rd() {
  long long x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
void out(long long a) {
  if (a < 0) putchar('-'), a = -a;
  if (a >= 10) out(a / 10);
  putchar(a % 10 + '0');
}
long long ksm(long long a, long long b, long long m) {
  long long ret = 1ll;
  while (b) {
    if (b & 1) ret *= a, ret %= m;
    a *= a, a %= m, b >>= 1;
  }
  return ret;
}
long long ksm(long long a, long long b) {
  long long ret = 1ll;
  while (b) {
    if (b & 1) ret *= a;
    a *= a, b >>= 1;
  }
  return ret;
}
long long inv(long long x, long long m) { return ksm(x, m - 2, m); }
const long long N = 2e5 + 400;
const long long INF = 1e17;
long long n, m, S, T;
struct Dinic {
  long long head[N], dep[N];
  long long ecnt;
  struct edge {
    long long v, next;
    long long flow;
  } e[N * 10];
  void init() {
    memset(head, -1, sizeof head);
    ecnt = 0;
  }
  void addedge(long long u, long long v, long long flow) {
    e[ecnt].v = v;
    e[ecnt].flow = flow;
    e[ecnt].next = head[u];
    head[u] = ecnt++;
    e[ecnt].v = u;
    e[ecnt].flow = 0;
    e[ecnt].next = head[v];
    head[v] = ecnt++;
  }
  bool BFS() {
    memset(dep, 0, sizeof dep);
    queue<long long> Q;
    Q.push(S);
    dep[S] = 1;
    while (!Q.empty()) {
      long long u = Q.front();
      Q.pop();
      for (long long i = head[u]; ~i; i = e[i].next) {
        if (e[i].flow && !dep[e[i].v]) {
          dep[e[i].v] = dep[u] + 1;
          Q.push(e[i].v);
        }
      }
    }
    return dep[T];
  }
  long long DFS(long long u, long long f) {
    if (u == T || f == 0) return f;
    long long w, used = 0;
    for (long long i = head[u]; ~i; i = e[i].next) {
      if (e[i].flow && dep[e[i].v] == dep[u] + 1) {
        w = DFS(e[i].v, min(f, e[i].flow));
        e[i].flow -= w;
        e[i ^ 1].flow += w;
        used += w;
        f -= w;
      }
    }
    if (!used) dep[u] = -1;
    return used;
  }
  long long maxflow() {
    long long ans = 0;
    while (BFS()) {
      ans += DFS(S, INF);
    }
    return ans;
  }
} dinic;
vector<pair<pair<long long, long long>, long long>> vec;
bool check(long long x) {
  dinic.init();
  S = 0, T = n * 2 + 50;
  for (long long i = 1; i <= n; i++)
    dinic.addedge(S, i, 1), dinic.addedge(i + n, T, 1);
  for (auto i : vec) {
    if (i.second <= x) {
      dinic.addedge(i.first.first, i.first.second, 1);
    }
  }
  return dinic.maxflow() >= n;
}
void run() {
  n = rd(), m = rd();
  while (m--) {
    long long u = rd(), v = rd() + n, w = rd();
    vec.push_back(make_pair(make_pair(u, v), w));
  }
  long long l = 1, r = 1e9, ans = -1;
  while (l <= r) {
    long long mid = l + r >> 1;
    if (check(mid))
      ans = mid, r = mid - 1;
    else
      l = mid + 1;
  }
  out(ans), puts("");
}
signed main() {
  run();
  return 0;
}
