#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define lint long long
#define pii pair<int, int>
#define FOR(i, a, b) for(int i = (a); i < (b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(v) (v).begin(), (v).end()
#define SZ(v) ((int)v.size())
#define ZERO(a) memset(a, 0, sizeof(a))
#define MINUS(a) memset(a, 0xff, sizeof(a))
#define MINF(a) memset(a, 0x3f, sizeof(a))
#define POW(n) (1LL << (n))
#define POPCNT(n) (__builtin_popcount(n))
#define IN(i, a, b) (a <= i && i <= b)
using namespace std;
template <typename T> inline bool CHMIN(T& a,T b) { if(a>b) { a=b; return 1; } return 0; }
template <typename T> inline bool CHMAX(T& a,T b) { if(a<b) { a=b; return 1; } return 0; }
template <typename T> inline void SORT(T& a) { sort(ALL(a)); }
template <typename T> inline void REV(T& a) { reverse(ALL(a)); }
template <typename T> inline void UNI(T& a) { sort(ALL(a)); a.erase(unique(ALL(a)),a.end()); }
template <typename T> inline T LB(vector<T>& v, T a) { return *lower_bound(ALL(v),a); }
template <typename T> inline int LBP(vector<T>& v, T a) { return lower_bound(ALL(v),a) - v.begin(); }
template <typename T> inline T UB(vector<T>& v, T a) { return *upper_bound(ALL(v),a); }
template <typename T> inline int UBP(vector<T>& v, T a) { return upper_bound(ALL(v),a) - v.begin(); }
template <typename T1, typename T2> ostream& operator<< (ostream& os, const pair<T1,T2>& p) { os << p.first << " " << p.second; return os; }
template <typename T1, typename T2> istream& operator>> (istream& is, pair<T1,T2>& p) { is >> p.first >> p.second; return is; }
template <typename T> ostream& operator<< (ostream& os, const vector<T>& v) { REP(i,v.size()) { if (i) os << " "; os << v[i]; } return os; }
template <typename T> istream& operator>> (istream& is, vector<T>& v) { for(T& in : v) is >> in; return is; }
template <typename T = int> vector<T> make_v(size_t a) { return vector<T>(a); }
template <typename T, typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...)); }
template <typename T, typename V> typename enable_if<is_class<T>::value == 0>::type fill_v(T &t, const V &v) { t = v; }
template <typename T, typename V> typename enable_if<is_class<T>::value != 0>::type fill_v(T &t, const V &v) { for(auto &e : t) fill_v(e, v); }
const lint MOD = 1000000007;
const lint INF = 0x3f3f3f3f3f3f3f3f;
const double PI = 3.14159265358979323846;
const double EPS = 1e-10;

template <typename T>
struct Edge {
    int from, to;
    T cost;
    Edge() {}
    Edge(int f, int t, T c) : from(f), to(t), cost(c) {}
};
template <typename T> using Edges = vector<Edge<T>>;


// Bellman-Fordのアルゴリズム
// 負辺があっても動作する．負閉路検出も行う
template <typename T> vector<T> bellman_ford(Edges<T> &es, int s, T inf = numeric_limits<T>::max()) {
    int n = 0;
    for (auto& e : es) n = max({n, e.from, e.to});
    ++n;
    vector<T> dis(n, inf);
    dis[s] = 0;
    for (int t = 0; t < n << 1; ++t) {
        for (auto& e : es) {
            if (dis[e.from] != inf && dis[e.to] > dis[e.from] + e.cost) {
                dis[e.to] = dis[e.from] + e.cost;
                if (t + 1 >= n) dis[e.to] = -inf;   // 頂点e.toは負閉路を経由して到達可能
            }
        }
    }
    return dis;
}

void _main() {
    int N, M;
    cin >> N >> M;
    Edges<int> es(M);
    REP (i, M) {
        int a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        es[i] = Edge<int>(a, b, -c);
    }
    auto dis = bellman_ford<int>(es, 0, INF);
    if (dis[N - 1] == -INF) cout << "inf" << endl;
    else cout << -dis[N - 1] << endl;
}

signed main(signed argc, char **argv) {
    if (argc > 1) {
        if (strchr(argv[1], 'i')) freopen("input.txt", "r", stdin);
        if (strchr(argv[1], 'o')) freopen("output.txt", "w", stdout);
    }
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(10);
    _main();
    return 0;
}

Measured memory_bytes: 256