#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 998244353;
// constexpr int MOD = 1000000007;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

template <typename CostType>
struct Edge {
  CostType cost;
  int src, dst;

  explicit Edge(const int src, const int dst, const CostType cost = 0)
      : cost(cost), src(src), dst(dst) {}

  auto operator<=>(const Edge& x) const = default;
};

template <typename CostType>
struct BellmanFord {
  const CostType inf;
  std::vector<CostType> dist;

  BellmanFord(const std::vector<std::vector<Edge<CostType>>>& graph,
              const CostType inf = std::numeric_limits<CostType>::max())
      : inf(inf), is_built(false), graph(graph) {}

  bool has_negative_cycle(const int s) {
    is_built = true;
    const int n = graph.size();
    dist.assign(n, inf);
    dist[s] = 0;
    prev.assign(n, -1);
    for (int step = 0; step < n; ++step) {
      bool is_updated = false;
      for (int i = 0; i < n; ++i) {
        if (dist[i] == inf) continue;
        for (const Edge<CostType>& e : graph[i]) {
          if (dist[e.dst] > dist[i] + e.cost) {
            dist[e.dst] = dist[i] + e.cost;
            prev[e.dst] = i;
            is_updated = true;
          }
        }
      }
      if (!is_updated) return false;
    }
    return true;
  }

  std::vector<int> build_path(int t) const {
    assert(is_built);
    std::vector<int> res;
    for (; t != -1; t = prev[t]) {
      res.emplace_back(t);
    }
    std::reverse(res.begin(), res.end());
    return res;
  }

 private:
  bool is_built;
  std::vector<int> prev;
  std::vector<std::vector<Edge<CostType>>> graph;
};

int main() {
  int n, m; cin >> n >> m;
  vector<int> A(n);
  for (int& A_i : A) cin >> A_i;
  vector<vector<Edge<ll>>> graph(n);
  while (m--) {
    int a, b, c; cin >> a >> b >> c; --a; --b;
    graph[a].emplace_back(a, b, c - A[a]);
  }
  BellmanFord<ll> bellman_ford(graph);
  if (bellman_ford.has_negative_cycle(0)) {
    cout << "inf\n";
  } else {
    cout << -bellman_ford.dist[n - 1] + A[n - 1] << '\n';
  }
  return 0;
}