#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
#include <limits>

#define rep(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
using ll = long long int;  // NOLINT
using P = pair<ll, ll>;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; debug_print(__VA_ARGS__); } while(false)
template<typename T, typename... Ts> void debug_print(const T &t, const Ts &...ts) { cerr << t; ((cerr << ", " << ts), ...); cerr << endl; }
#else
#define dump(...) do{ } while(false)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T> bool chmin(T &a, const T& b) { if (a > b) {a = b; return true; } return false; }
template<typename T> bool chmax(T &a, const T& b) { if (a < b) {a = b; return true; } return false; }
template<typename T, typename... Ts> void print(const T& t, const Ts&... ts) { cout << t; ((cout << ' ' << ts), ...); cout << '\n'; }
constexpr static struct PositiveInfinity { template<typename T> constexpr operator T() const { return numeric_limits<T>::max() / 2; } constexpr auto operator-() const; } inf;  // NOLINT
constexpr static struct NegativeInfinity { template<typename T> constexpr operator T() const { return numeric_limits<T>::lowest() / 2; } constexpr auto operator-() const; } NegativeInfinityVal;
constexpr auto PositiveInfinity::operator-() const { return NegativeInfinityVal; }
constexpr auto NegativeInfinity::operator-() const { return inf; }
// clang-format on

#include <limits>
#include <cmath>
#include <queue>
#include <deque>
enum class CostType {
    NoEdge,
    One,
    ZeroOne,
    Plus,
    PlusMinus,
};

template<typename Cost = long long, typename Vertex = int>
class Graph {
    using Edge = pair<Cost, Vertex>;
    using ShortestInfo = pair<vector<Cost>, vector<Vertex>>;

    vector<vector<Edge>> g;
    CostType cost_type;

    ShortestInfo no_edge(Vertex s) {
        auto costs = vector<Cost>(g.size(), Inf);
        auto prev = vector<Vertex>(g.size(), None);
        costs[s] = 0;
        return make_pair(std::move(costs), std::move(prev));
    }

    ShortestInfo bfs01(Vertex s) {
        auto [costs, prev] = no_edge(s);
        deque<Edge> deq;
        deq.emplace_back(0, s);
        while (deq.size()) {
            auto [c, v] = deq.front();
            deq.pop_front();
            if (costs[v] < c)
                continue;
            for (auto &&[nc, nv] : adjacent(v)) {
                if (costs[nv] > c + nc) {
                    costs[nv] = c + nc;
                    if (nc == 0) {
                        deq.emplace_front(c, nv);
                    } else {
                        deq.emplace_back(c + 1, nv);
                    }
                    prev[nv] = v;
                }
            }
        }
        return make_pair(std::move(costs), std::move(prev));
    }

    ShortestInfo bfs(Vertex s) {
        auto [costs, prev] = no_edge(s);
        queue<Edge> que;
        que.emplace(0, s);
        while (que.size()) {
            auto [c, v] = que.front();
            que.pop();
            if (costs[v] < c)
                continue;
            for (auto &&[nc, nv] : adjacent(v)) {
                if (costs[nv] > c + nc) {
                    costs[nv] = c + nc;
                    que.emplace(c + nc, nv);
                    prev[nv] = v;
                }
            }
        }
        return make_pair(std::move(costs), std::move(prev));
    }

    ShortestInfo dijkstra(Vertex s) {
        auto [costs, prev] = no_edge(s);
        priority_queue<Edge, vector<Edge>, greater<Edge>> pq;
        pq.emplace(0, s);
        while (pq.size()) {
            auto [c, v] = pq.top();
            pq.pop();
            if (costs[v] < c)
                continue;
            for (auto &&[nc, nv] : adjacent(v)) {
                if (costs[nv] > c + nc) {
                    costs[nv] = c + nc;
                    pq.emplace(c + nc, nv);
                    prev[nv] = v;
                }
            }
        }
        return make_pair(std::move(costs), std::move(prev));
    }

    ShortestInfo bellman_ford(Vertex s) {
        auto [costs, prev] = no_edge(s);
        for (size_t i = 0, n = g.size(); i < 2 * n; i++) {
            for (Vertex v = 0; v < static_cast<Vertex>(n); v++) {
                if (costs[v] == Inf)
                    continue;
                for (auto &&[cost, nv] : adjacent(v)) {
                    if (costs[v] == -Inf || costs[v] + cost < costs[nv]) {
                        if (i >= n) {
                            costs[nv] = -Inf;
                        } else {
                            costs[nv] = costs[v] + cost;
                        }
                        prev[nv] = v;
                    }
                }
            }
        }
        return make_pair(std::move(costs), std::move(prev));
    }

    void update_cost_type(Cost cost) {
        CostType ct = CostType::NoEdge;
        if (signbit(cost)) {
            ct = CostType::PlusMinus;
        } else if (cost != 0 && cost != 1) {
            ct = CostType::Plus;
        } else if (cost == 0) {
            ct = CostType::ZeroOne;
        } else if (cost == 1) {
            ct = CostType::One;
        }
        cost_type = static_cast<CostType>(max(static_cast<int>(ct), static_cast<int>(cost_type)));
    }

public:
    Graph(size_t n) : g(n), cost_type(CostType::NoEdge) {}
    void add_edge(Vertex s, Vertex t, Cost cost) {
        update_cost_type(cost);
        g[s].emplace_back(cost, t);
    }
    const vector<Edge> &adjacent(Vertex v) const {
        return g[v];
    }
    size_t size() const {
        return g.size();
    }

    CostType get_cost_type() const {
        return cost_type;
    }

    ShortestInfo shortest(Vertex s) {
        switch (cost_type) {
            case CostType::ZeroOne:
                return bfs01(s);
            case CostType::One:
                return bfs(s);
            case CostType::Plus:
                return dijkstra(s);
            case CostType::PlusMinus:
                return bellman_ford(s);
            case CostType::NoEdge:
                return no_edge(s);
        }
        __builtin_unreachable();
    }

    constexpr static Cost Inf = numeric_limits<Cost>::max();
    constexpr static Vertex None = -1;
};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    vector<int> tm(n);
    rep(i, 0, n) {
        cin >> tm[i];
    }

    Graph<ll> g(n);
    rep(i, 0, m) {
        int a, b, c;
        cin >> a >> b >> c;
        a--;
        b--;
        g.add_edge(a, b, c - tm[b]);
    }
    auto [cost, prev] = g.shortest(0);
    ll ans = cost[n - 1];
    if (ans == -g.Inf) {
        print("inf");
    } else {
        print(-ans + tm[0]);
    }

    return 0;
}