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

struct Edge {
    Edge() {}
    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;
};

struct Graph {
    private:
    int n, m;
    bool dir;
    vector<vector<Edge>> g;
    vector<Edge> e;
    
    public:
    Graph() {}
    Graph(int n_, bool dir_) : n(n_), m(0), dir(dir_), g(n), e(0) {}
    Graph(int n_) : n(n_), m(0), dir(false), g(n), e(0) {}
    
    int size() {
        return n;
    }
    
    int edgesize() {
        return m;
    }
    
    bool directed() {
        return dir;
    }
    
    void add(int u, int v, long long w) {
        g[u].emplace_back(u, v, w, m);
        e.emplace_back(u, v, w, m);
        if (!dir) {
            g[v].emplace_back(v, u, w, m);
        }
        m++;
    }
    
    vector<Edge> operator[](int v) {
        return g[v];
    }
    
    Edge edge(int i) {
        return e[i];
    }
};

pair<vector<long long>, vector<bool>> BellmanFord(Graph g, int s) {
    int n = g.size(), m = g.edgesize();
    long long INF = 1000000000000000000;
    vector<long long> dist(n, INF);
    vector<bool> nega(n, false);
    dist[s] = 0;
    for (int i = 0; i < n - 1; i++) {
        for (int j = 0; j < m; j++) {
            auto e = g.edge(j);
            int u = e.from, v = e.to;
            long long w = e.cost;
            if (dist[u] != INF && dist[v] > dist[u] + w) {
                dist[v] = dist[u] + w;
            }
        }
    }
    vector<long long> d2 = dist;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            auto e = g.edge(j);
            int u = e.from, v = e.to;
            long long w = e.cost;
            if (d2[u] != INF && d2[v] > d2[u] + w) {
                d2[v] = d2[u] + w;
                nega[v] = true;
            }
            if (nega[u]) {
                nega[v] = true;
            }
        }
    }
    return {dist, nega};
}

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