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