#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  VI A(n);
  rep(i, n) cin >> A[i];
  vector<vector<P>> to(n + 1);
  rep(_, m) {
    int a, b, c;
    cin >> a >> b >> c;
    a--, b--;
    to[a].emplace_back(b, c - A[a]);
  }
  to[n - 1].emplace_back(n, -A[n - 1]);
  constexpr long long INF = 1002003004005006007;
  n++;
  VL dist(n, INF);
  dist[0] = 0;
  rep(_, n) {
    rep(u, n) if (dist[u] != INF) for (auto [v, c] : to[u]) chmin(dist[v], dist[u] + c);
  }
  VL dist_pre = dist;
  rep(_, n) {
    rep(u, n) if (dist[u] != INF) for (auto [v, c] : to[u]) chmin(dist[v], dist[u] + c);
  }
  rep(u, n) if (dist[u] < dist_pre[u]) dist[u] = -INF;
  rep(_, n) {
    rep(u, n) if (dist[u] == -INF) for (auto [v, c] : to[u]) dist[v] = -INF;
  }
  if (dist[n - 1] == -INF) cout << "inf" << '\n';
  else cout << -dist[n - 1] << '\n';
}