using System;
using System.Linq;
using System.Collections.Generic;
using Debug = System.Diagnostics.Debug;
using StringBuilder = System.Text.StringBuilder;
using Number = System.Int64;
using static System.Math;
namespace Program
{
    public class Solver
    {
        public void Solve()
        {
            var n = ri;
            var m = ri;
            var G = Enumerate(n, x => new List<Edge>());
            for (int i = 0; i < m; i++)
            {
                var a = ri - 1;
                var b = ri - 1;
                var c = -ri;
                Debug.WriteLine("{0} {1} {2}", a, b, c);
                G[a].Add(new Edge(a, b, c));
            }
            var dist = new long[n];
            G.BellmanFord(0, out dist);
            if (dist[n - 1] != -1L << 60)
                IO.Printer.Out.WriteLine(-dist[n - 1]);
            else IO.Printer.Out.WriteLine("inf");

        }
        int ri => sc.Integer();
        long rl => sc.Long();
        double rd => sc.Double();
        string rs => sc.Scan();


        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region main
static class Ex
{
    static public string AsString(this IEnumerable<char> ie) { return new string(System.Linq.Enumerable.ToArray(ie)); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") { return string.Join(st, ie); }
    static public void Main()
    {
        var solver = new Program.Solver();
        solver.Solve();
        Program.IO.Printer.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO
{
    using System.IO;
    using System.Text;
    using System.Globalization;
    public class Printer: StreamWriter
    {
        static Printer() { Out = new Printer(Console.OpenStandardOutput()) { AutoFlush = false }; }
        public static Printer Out { get; set; }
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(System.IO.Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
        public Printer(System.IO.Stream stream, Encoding encoding) : base(stream, encoding) { }
        public void Write<T>(string format, T[] source) { base.Write(format, source.OfType<object>().ToArray()); }
        public void WriteLine<T>(string format, T[] source) { base.WriteLine(format, source.OfType<object>().ToArray()); }
    }
    public class StreamScanner
    {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read()
        {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine()
        {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n'; b = (char)read())
                if (b == 0) break;
                else if (b != '\r') sb.Append(b);
            return sb.ToString();
        }
        public long Long()
        {
            if (isEof) return long.MinValue;
            long ret = 0; byte b = 0; var ng = false;
            do b = read();
            while (b != 0 && b != '-' && (b < '0' || '9' < b));
            if (b == 0) return long.MinValue;
            if (b == '-') { ng = true; b = read(); }
            for (; true; b = read())
            {
                if (b < '0' || '9' < b)
                    return ng ? -ret : ret;
                else ret = ret * 10 + b - '0';
            }
        }
        public int Integer() { return (isEof) ? int.MinValue : (int)Long(); }
        public double Double() { var s = Scan(); return s != "" ? double.Parse(s, CultureInfo.InvariantCulture) : double.NaN; }
        private T[] enumerate<T>(int n, Func<T> f)
        {
            var a = new T[n];
            for (int i = 0; i < n; ++i) a[i] = f();
            return a;
        }

        public char[] Char(int n) { return enumerate(n, Char); }
        public string[] Scan(int n) { return enumerate(n, Scan); }
        public double[] Double(int n) { return enumerate(n, Double); }
        public int[] Integer(int n) { return enumerate(n, Integer); }
        public long[] Long(int n) { return enumerate(n, Long); }
    }
}
#endregion
#region Edge
public struct Edge: IComparable<Edge>
{
    public int from, to, id;
    public long cost;
    public Edge(int f, int t) : this() { from = f; to = t; cost = 0; id = -1; }
    public Edge(int f, int t, long v) : this() { from = f; to = t; cost = v; id = -1; }
    public Edge(int f, int t, long v, int idx) : this() { from = f; to = t; cost = v; id = idx; }
    public override string ToString() { return string.Format("{0}->{1}:{2} id:{3}", from, to, cost, id); }
    public int CompareTo(Edge other)
    {
        var cmp = cost.CompareTo(other.cost);
        if (cmp != 0) return cmp;
        cmp = to.CompareTo(other.to);
        if (cmp != 0) return cmp;
        cmp = from.CompareTo(other.from);
        return id.CompareTo(other.id);
    }
}
#endregion
#region bellman_ford
static partial class Graph
{
    //O(|V||E|)
    static public bool BellmanFord(this List<Edge>[] graph, int s, out long[] dist, out int[] prev)
    {
        const long max = 1L << 60;
        var n = graph.Length;
        dist = new long[n];
        prev = new int[n];
        for (int i = 0; i < n; i++)
        {
            dist[i] = max;
            prev[i] = -1;
        }
        dist[s] = 0;
        var negCycle = false;
        for (int i = 0; i < n; i++)
            for (int v = 0; v < n; v++)
                foreach (var np in graph[v])
                {
                    if (dist[np.to] <= np.cost + dist[v])
                        continue;
                    dist[np.to] = np.cost + dist[v];
                    prev[np.to] = v;
                    if (i != n - 1)
                        continue;
                    dist[np.to] = -max;
                    negCycle = true;
                }
        return negCycle;
    }
}

static partial class Graph
{
    static public bool BellmanFord(this List<Edge>[] graph, int s, out long[] dist)
    {
        const long max = 1L << 60;
        var n = graph.Length;
        dist = new long[n];
        for (int i = 0; i < n; i++)
            dist[i] = max;
        dist[s] = 0;
        var negCycle = false;
        for (int i = 0; i < n; i++)
            for (int v = 0; v < n; v++)
                foreach (var np in graph[v])
                {
                    if (dist[np.to] <= np.cost + dist[v])
                        continue;
                    dist[np.to] = np.cost + dist[v];
                    if (i != n - 1)
                        continue;
                    dist[np.to] = -max;
                    negCycle = true;
                }
        return negCycle;
    }
}
static partial class Graph
{
    static public void BellmanFord(this Edge[] edges, int s, long[] dist)
    {
        const long max = 1L << 60;
        var n = dist.Length;
        for (int i = 0; i < n; i++)
            dist[i] = max;
        dist[s] = 0;
        while (true)
        {
            var update = false;
            foreach (var e in edges)
            {
                if (dist[e.from] + e.cost < dist[e.to])
                {
                    dist[e.to] = dist[e.from] + e.cost;
                    update = true;
                }

            }
            if (!update) break;
        }

    }
}
#endregion

Measured memory_bytes: 13396