#include <bits/stdc++.h>
using namespace std;

struct Edge {
    Edge() {}
    Edge(int to_, long long cost_) : to(to_), cost(cost_) {}
    Edge(int from_, int to_, long long cost_) : from(from_), to(to_), cost(cost_) {}
    Edge(int from_, int to_, long long cost_, int idx_) : from(from_), to(to_), cost(cost_), idx(idx_) {}
    
    int from, to;
    long long cost;
    int idx;
};

using Graph = vector<vector<Edge>>;
#define add emplace_back

vector<long long> BellmanFord(Graph g, int s) {
    int n = g.size();
    long long INF = 1000000000000000000;
    vector<long long> dist(n, INF);
    vector<bool> nega(n, false);
    dist[s] = 0;
    for (int step = 0; step < n - 1; step++) {
        bool update = false;
        for (int u = 0; u < n; u++) {
            if (dist[u] == INF) {
                continue;
            }
            for (auto e : g[u]) {
                int v = e.to;
                long long w = e.cost;
                if (dist[v] > dist[u] + w) {
                    dist[v] = dist[u] + w;
                    update = true;
                }
            }
        }
        if (!update) {
            break;
        }
    }
    for (int step = 0; step < n; step++) {
        for (int u = 0; u < n; u++) {
            if (dist[u] == INF) {
                continue;
            }
            for (auto e : g[u]) {
                int v = e.to;
                long long w = e.cost;
                if (dist[v] > dist[u] + w) {
                    dist[v] = dist[u] + w;
                    nega[v] = true;
                }
                if (nega[u]) {
                    nega[v] = true;
                }
            }
        }
    }
    for (int v = 0; v < n; v++) {
        if (nega[v]) {
            dist[v] = -INF;
        }
    }
    return dist;
}

using lint = long long;

int main() {
    int n, m;
    cin >> n >> m;
    vector<lint> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    Graph g(n);
    for (int i = 0; i < m; i++) {
        int u, v;
        lint w;
        cin >> u >> v >> w;
        u--;
        v--;
        g[u].add(v, w - a[v]);
    }
    auto d = BellmanFord(g, 0);
    if (d[n - 1] == -1000000000000000000) {
        cout << "inf" << endl;
    } else {
        cout << -(d[n - 1] - a[0]) << endl;
    }
}