#include <bits/stdc++.h>
#ifdef LOCAL
#include "./debug.cpp"
#else
#define debug(...)
#define print_line
#endif
using namespace std;
using ll = long long;

int main() {
    int N, M;
    cin >> N >> M;
    vector<ll> A(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i];
    }
    vector<vector<pair<int, ll>>> G(N);
    vector<vector<int>> rG(N);
    for (int i = 0; i < M; i++) {
        int a, b;
        ll c;
        cin >> a >> b >> c;
        a--;
        b--;
        G[a].push_back({b, c});
        rG[b].push_back(a);
    }

    vector<bool> reach(N, false);
    reach[N - 1] = true;
    queue<int> Q;
    Q.push(N - 1);
    while (!Q.empty()) {
        int now = Q.front();
        Q.pop();
        for (auto nxt : rG[now]) {
            if (reach[nxt]) {
                continue;
            }
            reach[nxt] = true;
            Q.push(nxt);
        }
    }

    vector<ll> dst(N, LLONG_MIN);
    dst[0] = A[0];
    for (int i = 0; i < N; i++) {
        bool fin = true;
        for (int j = 0; j < N; j++) {
            if (!reach[j] || dst[j] == LLONG_MIN) {
                continue;
            }
            for (auto [nxt, cost] : G[j]) {
                if (dst[nxt] < dst[j] - cost + A[nxt]) {
                    dst[nxt] = dst[j] - cost + A[nxt];
                    fin = false;
                }
            }
        }
        if (fin) {
            break;
        }
        if (i == N - 1) {
            cout << "inf" << endl;
            return 0;
        }
    }
    cout << dst[N - 1] << endl;
}