#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit(b) (1ll << (b))
#define uniq(v) (v).erase(unique(all(v)), (v).end())

using namespace std;

using i32 = int;
using i64 = long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vf80 = vector<f80>;
using vstr = vector<string>;

inline void yes() { cout << "Yes" << '\n'; exit(0); }
inline void no() { cout << "No" << '\n'; exit(0); }
inline i64 gcd(i64 a, i64 b) { if (min(a, b) == 0) return max(a, b); if (a % b == 0) return b; return gcd(b, a % b); }
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; }
template <typename T> class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T> class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) { if (x < y) x = y; }
template <typename T> inline void amin(T &x, T y) { if (x > y) x = y; }
template <typename T> inline T power(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
template <typename T> istream& operator>>(istream &is, vector<T> &v) { each(x, v) is >> x; return is; }
template <typename T> ostream& operator<<(ostream &os, vector<T> &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; }
template <typename T, typename S> istream& operator>>(istream &is, pair<T, S> &p) { is >> p.first >> p.second; return is; }
template <typename T, typename S> ostream& operator<<(ostream &os, pair<T, S> &p) { cout << p.first << ' ' << p.second; return os; }

template <typename T>
struct WeightedGraph {
  struct Edge {
    int to;
    T cost;
  };
  vector<vector<Edge>> edges;
  int n;
  WeightedGraph(int n) : n(n) {
    edges = vector<vector<Edge>>(n);
  }
  void add_edge(int from, int to, T cost = 0) {
    edges[from].push_back((Edge) { to, cost });
  }
  vector<Edge>& operator[](int x) {
    return edges[x];
  }
};

template <typename T>
vector<T> bellman_ford(WeightedGraph<T> &g, int s) {
  const T INF = numeric_limits<T>::max();

  vector<T> dist(g.n, INF);
  dist[s] = 0;

  i64 d;
  rep(i, g.n - 1) rep(v, g.n) each(e, g[v]) {
    if (dist[v] == INF) continue;
    if (dist[e.to] <= dist[v] + e.cost) continue;
    dist[e.to] = dist[v] + e.cost;
  }
  d = dist[g.n - 1];
  rep(i, g.n) rep(v, g.n) each(e, g[v]) {
    if (dist[v] == INF) continue;
    if (dist[e.to] <= dist[v] + e.cost) continue;
    dist[e.to] = dist[v] + e.cost;
  }
  if (d != dist[g.n - 1]) return vector<T>();
  
  return dist;
}

void solve() {
  int N, M; cin >> N >> M;
  auto g = WeightedGraph<i64>(N);
  rep(i, M) {
    int a, b, c; cin >> a >> b >> c;
    a--, b--;
    g.add_edge(a, b, -c);
  }
  auto ans = bellman_ford(g, 0);
  if (ans.size() == 0) {
    cout << "inf" << '\n';
  } else {
    cout << -ans[N - 1] << '\n';
  }
}


Measured memory_bytes: 384