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

//#include <boost/multiprecision/cpp_int.hpp>
// using namespace boost::multiprecision;
// using cint = cpp_int;
//#pragma GCC optimize("", on)
//#pragma GCC optimization_level 3
//#define min(...) min({...})
//#define max(...) max({...})
//#define x first
//#define y second

// Define
using ll = long long;
using ull = unsigned long long;
using ld = long double;
const ll dx[4] = {1, 0, -1, 0};
const ll dy[4] = {0, 1, 0, -1};
const ll MOD = 1e9 + 7;
const ll inf = 1 << 30;
// const ll INF = LONG_MAX;
const ll INF = 1LL << 60;
const ull MAX = ULONG_MAX;
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define endl '\n'
#define space ' '
#define def inline auto
#define func inline constexpr ll
#define run __attribute__((constructor)) def _
#define all(v) begin(v), end(v)
#define input(a) scanf("%lld", &(a))
#define print(a) printf("%lld\n", (a))
#define ok(a, b) (0 <= (a) && (a) < (b))

// Debug
#define debug(...)                                                             \
    {                                                                          \
        cerr << __LINE__ << ": " << #__VA_ARGS__ << " = ";                     \
        for (auto &&X : {__VA_ARGS__}) cerr << "[" << X << "] ";               \
        cerr << endl;                                                          \
    }

#define dump(a, h, w)                                                          \
    {                                                                          \
        cerr << __LINE__ << ": " << #a << " = [" << endl;                      \
        rep(__i, h) {                                                          \
            rep(__j, w) cerr << a[__i][__j] << space;                          \
            cerr << endl;                                                      \
        }                                                                      \
        cerr << "]" << endl;                                                   \
    }

#define vdump(a, n)                                                            \
    {                                                                          \
        cerr << __LINE__ << ": " << #a << " = [";                              \
        rep(__i, n) if (__i) cerr << space << a[__i];                          \
        else cerr << a[__i];                                                   \
        cerr << "]" << endl;                                                   \
    }

struct edge {
    ll to, cost;
    edge(ll a, ll b) : to(a), cost(b) {}
};

struct position {
    ll x, y;
    position() {}
    position(ll a, ll b) : x(a), y(b) {}
    position next(ll k) { return {x + dx[k], y + dy[k]}; }
    bool operator==(position a) { return x == a.x && y == a.y; }
    bool operator!=(position a) { return !(position(x, y) == a); }
    bool operator<(position a) { return x ^ a.x ? x < a.x : y < a.y; }
    bool operator>(position a) { return x ^ a.x ? x > a.x : y > a.y; }
    bool operator<=(position a) { return x ^ a.x ? x < a.x : y <= a.y; }
    bool operator>=(position a) { return x ^ a.x ? x > a.x : y >= a.y; }
};

struct Range {
    ll left, right;
    Range() {}
    Range(ll l, ll r) : left(l), right(r) {}
    ll length() { return right - left; }
    bool operator==(Range A) { return left == A.left && right == A.right; }
    bool operator!=(Range A) { return !(Range(left, right) == A); }
    bool operator>(Range A) { return left < A.left && right > A.right; }
    bool operator<(Range A) { return left > A.left && right < A.right; }
    bool operator>=(Range A) { return left <= A.left && right >= A.right; }
    bool operator<=(Range A) { return left >= A.left && right <= A.right; }
};

// Loop
#define inc(i, a, n) for (ll i = (a), _##i = (n); i <= _##i; ++i)
#define dec(i, a, n) for (ll i = (a), _##i = (n); i >= _##i; --i)
#define rep(i, n) for (ll i = 0, _##i = (n); i < _##i; ++i)
#define each(i, a) for (auto &&i : a)
#define loop() for (;;)

// Stream
#define fout(n) cout << fixed << setprecision(n)
#define fasten cin.tie(0), ios::sync_with_stdio(0)

// Speed
run() { fasten, fout(10); }
#pragma GCC optimize("O3")
#pragma GCC target("avx")

// Math
func gcd(ll a, ll b) { return b ? gcd(b, a % b) : a; }
func lcm(ll a, ll b) { return a * b / gcd(a, b); }
func sign(ll a) { return a ? abs(a) / a : 0; }

template <class T> def in() {
    T A;
    cin >> A;
    return A;
}

struct BellmanFord {
    using graph = vector<vector<edge>>;
    ll N;
    graph G;
    vector<ll> dist, from;
    vector<bool> error_loop;
    BellmanFord(ll n) : N(n), G(n), dist(n), from(n), error_loop(n) {}
    void setDist(ll from, ll to, ll cost) { G[from].push_back(edge(to, cost)); }
    void culc(ll start = 0) {
        fill(all(dist), INF);
        fill(all(from), -1);
        fill(all(error_loop), false);
        dist[start] = 0;
        rep(i, N - 1) rep(j, N) rep(k, G[j].size()) {
            ll to = G[j][k].to;
            if (dist[j] == INF) continue;
            if (dist[to] > dist[j] + G[j][k].cost) {
                dist[to] = dist[j] + G[j][k].cost;
                from[to] = j;
            }
        }
        rep(i, N) rep(j, N) rep(k, G[j].size()) {
            ll to = G[j][k].to;
            if (dist[j] == INF) continue;
            if (dist[to] > dist[j] + G[j][k].cost) error_loop[to] = true;
            if (error_loop[j]) error_loop[to] = true;
        }
    }
};

signed main() {
    ll N, M, A, B, C;
    cin >> N >> M;
    BellmanFord BF(N);
    rep(i, M) {
        cin >> A >> B >> C;
        BF.setDist(A - 1, B - 1, -C);
    }
    BF.culc();
    if (BF.error_loop[N - 1]) return puts("inf") & 0;
    cout << -BF.dist[N - 1] << endl;
}

// for compilation: g++ -Ofast -march=native -o _ _.cpp -std=c++17


Measured memory_bytes: 384