#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

struct Edge {
    const unsigned int from;
    const unsigned int to;
    const long long cost;

    Edge(unsigned int from, unsigned int to, long long cost) : from(from), to(to), cost(cost) {}

    bool operator<(const Edge& edge) const {
        return this->cost < edge.cost;
    }
    bool operator>(const Edge& edge) const {
        return this->cost > edge.cost;
    }
};


/**
 * startから他のすべてのnodeへの最短距離(到達できないnodeはLONG_LONG_MAX)をもとめる
 * 負の閉路がある場合は空を返す
 * O(|V||E|)
 */
std::vector<long long> bellman_ford(const int start, const int num_node, const std::vector<Edge> &edges) {
    std::vector<long long> distance(num_node, LONG_LONG_MAX);
    distance[start] = 0;
    std::vector<unsigned int> prev(num_node, -1);

    int i;
    for (i = 0; i < num_node; ++i) {
        bool update = false;
        for (const auto &e : edges) {
            unsigned int from = e.from, to = e.to;
            long long cost = e.cost;
            if (distance.at(from) != LONG_LONG_MAX and distance.at(to) > distance.at(from) + cost) {
                distance.at(to) = distance.at(from) + cost;
                prev.at(to) = from;
                update = true;
            }
        }
        if (not update) { break; }
    }

    if (i == num_node) {
        return {};
    }
    else {
        return distance;
    }
}


int main() {
    cin.tie(0);
	ios::sync_with_stdio(false);

	int N, M;
	cin >> N >> M;

	vector<Edge> edges1, edges2;
	vector<tuple<int, int, int>> v;
	FOR(_, 0, M) {
	    int a, b, c;
	    cin >> a >> b >> c;
	    a--; b--;
	    v.emplace_back(make_tuple(a, b, c));
	    edges1.emplace_back(Edge(b, a, 0));
	}

    auto dist1 = bellman_ford(N - 1, N, edges1);
	FOE(t, v) {
	    int a, b, c;
	    tie(a, b, c) = t;
	    if (dist1[a] != LONG_LONG_MAX and dist1[b] != LONG_LONG_MAX) {
            edges2.emplace_back(Edge(a, b, -c));
        }
    }

	auto dist = bellman_ford(0, N, edges2);
	if (dist.size() == 0) {
	    print("inf");
	}
	else {
	    print(-dist[N - 1]);
	}

	return 0;
}

Measured memory_bytes: 384