#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>
#include <queue>
#include <stack>
#include <numeric>
#include <unordered_set>
#include <unordered_map>

using namespace std;

typedef long long int ll;
typedef pair<int, int> Pii;

const ll mod = 998244353;

struct Edge {
  int from, to;
  ll cost;
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, m;
  cin >> n >> m;
  vector<ll> a(n);
  for (auto &x: a) cin >> x;
  vector<vector<Edge>> edges(n);
  for (int i = 0; i < m; i++) {
    int u, v;
    ll c;
    cin >> u >> v >> c;
    u--; v--;
    edges[u].push_back(Edge({u, v, c - a[v]}));
  }

  vector<ll> dist(n, 1e18);
  dist[0] = -a[0];
  for (int i = 0; i < n * 2; i++) {
    for (int j = 0; j < n; j++) {
      for (auto &e: edges[j]) {
        if (dist[e.from] + e.cost < dist[e.to]) {
          dist[e.to] = dist[e.from] + e.cost;
        }
      }
    }
  }
  for (int i = 0; i < n; i++) {
    for (auto &e: edges[i]) {
      if (dist[e.from] + e.cost < dist[e.to]) {
        cout << "inf" << endl;
        return 0;
      }
    }
  }

  cout << -dist[n - 1] << endl;

  return 0;
}