#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n, m;
  cin >> n >> m;
  vector<ll> a(n);
  rep(i, n) cin >> a[i];
  vector g(n, vector<pair<ll, ll>>());
  vector r(n, vector<ll>());
  rep(i, m) {
    ll u, v, c;
    cin >> u >> v >> c, u--, v--;
    g[u].emplace_back(v, c);
    r[v].push_back(u);
  }
  vector<bool> vis1(n, false), vis2(n, false);
  {
    vis1[0] = vis2[n - 1] = true;
    auto dfs1 = [&](auto self, ll u, ll p) -> void {
      for (const auto &[v, c] : g[u]) {
        if (v == p || vis1[v])
          continue;
        vis1[v] = true;
        self(self, v, u);
      }
    };
    auto dfs2 = [&](auto self, ll u, ll p) -> void {
      for (const auto v : r[u]) {
        if (v == p || vis2[v])
          continue;
        vis2[v] = true;
        self(self, v, u);
      }
    };
    dfs1(dfs1, 0, -1);
    dfs2(dfs2, n - 1, -1);
  }
  vector<ll> score(n, 0);
  bool updated = true;
  ll update_count = 0;
  while (updated) {
    updated = false;
    update_count += 1;
    if (update_count > n + 5) {
      cout << "inf\n";
      return;
    }
    vector<ll> nex = score;
    rep(u, n) if (vis1[u] && vis2[u]) {
      for (const auto &[v, c] : g[u])
        if (vis1[v] && vis2[v]) {
          ll now = score[u] - a[u] + c;
          if (now < nex[v]) {
            updated = true;
            nex[v] = now;
          }
        }
    }
    score = nex;
  }
  cout << -score[n - 1] + a[n - 1] << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}