#include <bits/stdc++.h>
#include <atcoder/modint>
using mint = atcoder::modint998244353;
using namespace std;
using ll = long long;
using ld = long double;
template <class T = ll>
using vc = vector<T>;
template <class T = ll>
using vvc = vc<vc<T>>;
void solve();
int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(20);
    ll t = 1;
    // cin >> t;
    for (int i = 1; i <= t; i++) solve();
    return 0;
}
#define rep(i, a, b) for (ll i = (a); i < (b); i++)
ll dy[4] = {0, 1, 0, -1}, dx[4] = {1, 0, -1, 0};
struct Edge {
    ll from, to, cost;
    Edge(ll from, ll to, ll cost) : from(from), to(to), cost(cost) {}
};
void solve() {
    ll n, m;
    cin >> n >> m;
    vc<ll> A(n);
    rep(i, 0, n) cin >> A[i];
    vc<Edge> edges;
    const ll INF = 1LL << 60;
    auto bell = [&](vc<ll>& dist) -> bool {
        dist[0] = 0;
        rep(i, 0, n) {
            bool update = false;
            for (auto e : edges) {
                if (dist[e.from] == INF) continue;
                if (dist[e.to] > dist[e.from] + e.cost) {
                    dist[e.to] = dist[e.from] + e.cost;
                    update = true;
                }
            }
            if (!update) return false;
        }
        rep(i, 0, n) {
            for (auto e : edges) {
                if (dist[e.from] == INF) continue;
                if (dist[e.to] > dist[e.from] + e.cost) {
                    dist[e.to] = -INF;
                }
            }
        }
        return true;
    };
    vc<ll> dist(n, INF);
    rep(i, 0, m) {
        ll a, b, c;
        cin >> a >> b >> c;
        a--, b--;
        edges.push_back(Edge(a, b, c - A[b]));
    }
    bell(dist);
    if (dist[n - 1] == -INF) {
        cout << "inf" << endl;
        return;
    }
    cout << A[0] - dist[n - 1] << endl;
}