#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);
    for (int i = 0; i < M; i++) {
        int a, b;
        ll c;
        cin >> a >> b >> c;
        a--;
        b--;
        G[a].push_back({b, c});
    }

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