#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  int n, m;
  cin >> n >> m;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  vector Edges(m, tuple<int, int, ll>());
  for (auto&& [from, to, cost] : Edges) cin >> from >> to >> cost, --from, --to;
  constexpr ll INF = 1e18;
  vector<ll> dist(n, INF);
  dist[n - 1] = -a[n - 1];
  rep(i, n) {
    for (auto&& [from, to, _cost] : Edges) {
      ll cost = _cost - a[from];
      if (dist[to] == INF) continue;
      if (dist[from] > dist[to] + cost) {
        dist[from] = dist[to] + cost;
        if (i == n - 1) {
          cout << "inf" << endl;
          return 0;
        }
      }
    }
  }
  cout << -dist[0] << endl;
  return 0;
}