#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, a, b) for (int i = (a); i < (b); ++i)
#define rrep(i, n) for (int i = (n)-1; i >= 0; --i)
#define rrep2(i, a, b) for (int i = (a)-1; i >= b; --i)
#define range(i, a, b, c) for (int i = a;             \
                               c > 0 ? i < b : i > b; \
                               i += c)
#define chmax(a, b) (a = (a) < (b) ? (b) : (a))
#define chmin(a, b) (a = (a) > (b) ? (b) : (a))
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(a) begin(a), end(a)
#define ifnot(a) if (not(a))
#define dump(x) cerr << #x << " = " << (x) << endl
#define int long long
#ifdef _MSC_VER
const bool test = true;
#else
const bool test = false;
#endif

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};
const int INF = (int)1 << 60;
const ll INFL = (ll)1 << 60;
ll mod_n = (int)1e9 + 7;
const double eps = 1e-10;
typedef long double Real;
// return -1, 0, 1
int sgn(const Real &r) { return (r > eps) - (r < -eps); }
int sgn(const Real &a, const Real &b) { return sgn(a - b); }

//.....................
const int MAX = (int)2e5 + 5;

vector<string> split(const string &str, char sep)
{
    vector<string> v;
    stringstream ss(str);
    string buffer;
    while (getline(ss, buffer, sep))
    {
        v.push_back(buffer);
    }
    return v;
}

template <class InputIterator>
int sum(InputIterator begin, InputIterator end)
{
    return accumulate(begin, end, 0ll);
}

void solve();

signed main()
{
    cout << fixed << setprecision(20);
    solve();
    while (true)
    {
        char s[MAX];
        if (scanf("%s", s) == EOF)
            break;
        int n = strlen(s);
        for (int i = n - 1; i > -1; i--)
        {
            ungetc(s[i], stdin);
        }
        solve();
    }
    return 0;
}

struct Vertex {
	int id, dist;
	bool operator > (const Vertex& r) const { return dist > r.dist; }
};

int N, M;
vector<Vertex> graph[MAX];
int d[MAX];

void solve()
{
    cin >> N >> M;
    rep(i, M) {
        int a, b, c;
        cin >> a >> b >> c;
        a--;
        b--;
        Vertex vertex;
        vertex.id = b;
        vertex.dist = c;
        graph[a].push_back(vertex);
    }
    rep(i, N) d[i] = -INF;
    d[0] = 0;

    bool update = true;
    rep(loop, 4)
    {
        update = false;
        rep(i, N + 100)
        {
            rep(j, N)
            {
                rep(k, (int)graph[j].size())
                {
                    // dump(graph[j][k].id);
                    // dump(graph[j][k].dist);
                    if (d[graph[j][k].id] < d[j] + graph[j][k].dist)
                    {
                        d[graph[j][k].id] = d[j] + graph[j][k].dist;
                        if (graph[j][k].id == N - 1) {
                            update = true;
                        }
                    }
                }
            }
        }
        if (update == false)
        {
            // rep(i, N) {
            //     cout << d[i] << endl;
            // }
            cout << d[N - 1] << endl;
            return;
        }
    }
    cout << "inf" << endl;
}


Measured memory_bytes: 4992