#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)
#define all(a) (a).begin(),(a).end()

const ll INF = 1ll << 60;

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    int N, M;
    cin >> N >> M;
    vector<ll> A(N);
    rep(i, 0, N) cin >> A[i];
    
    vector<vector<pair<int, ll>>> G(N);
    rep(i, 0, M) {
        int a, b;
        ll c;
        cin >> a >> b >> c;
        --a, --b;
        G[a].push_back({b, c - A[b]});
    }
    
    vector<ll> dist(N, INF);
    dist[0] = -A[0];
    rep(t, 0, N - 1) {
        rep(v, 0, N) {
            if (dist[v] == INF) continue;
            for (auto e : G[v]) {
                dist[e.first] = min(dist[e.first], dist[v] + e.second);
            }
        }
    }
    
    ll ans = -dist[N - 1];
    
    rep(t, 0, N) {
        rep(v, 0, N) {
            if (dist[v] == INF) continue;
            for (auto e : G[v]) {
                if (dist[e.first] > dist[v] + e.second) dist[e.first] = -INF;
            }
        }
    }
    
    if (dist[N - 1] == -INF) cout << "inf\n";
    else cout << ans << '\n';
}