using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var N = sc.ReadInt();
        var M = sc.ReadInt();
        var bf = new BellmanFord(N);
        for (int i = 0; i < M; i++)
        {
            var a = sc.ReadInt() - 1;
            var b = sc.ReadInt() - 1;
            var c = sc.ReadInt();
            bf.Add(a, b, -c);
        }
        bf.CalcDistance(0);
        var ans = -bf.Distances[N - 1];
        if (bf.Loop)
        {
            Console.WriteLine("inf");
        }
        else
        {
            Console.WriteLine(ans);
        }
    }

    class BellmanFord
    {
        public List<Edge> Edges { get; set; }
        public int VertexCount { get; set; }
        public long[] Distances { get; set; }
        public bool Loop { get; set; }
        public BellmanFord(int vertexCount)
        {
            this.VertexCount = vertexCount;
            this.Edges = new List<Edge>();
        }

        public void Add(int from, int to, int cost)
        {
            this.Edges.Add(new Edge(from, to, cost));
        }

        public void CalcDistance(int start)
        {
            this.Distances = new long[VertexCount];
            for (int i = 0; i < VertexCount; i++)
            {
                this.Distances[i] = long.MaxValue;
            }
            this.Distances[start] = 0;

            for (int i = 0; i < this.VertexCount; i++)
            {
                foreach (var e in this.Edges)
                {
                    var cost = this.Distances[e.From] + e.Cost;
                    if (this.Distances[e.From] != long.MaxValue && cost < this.Distances[e.To])
                    {
                        this.Distances[e.To] = cost;
                    }
                }
            }

            // 負の閉路判定
            this.Loop = false;
            for (int i = 0; i < this.VertexCount; i++)
            {
                foreach (var e in this.Edges)
                {
                    var cost = this.Distances[e.From] + e.Cost;
                    if (this.Distances[e.From] != long.MaxValue && cost < this.Distances[e.To])
                    {
                        this.Distances[e.To] = cost;
                        if (e.To == this.VertexCount - 1) this.Loop = true;
                    }
                }
            }
        }
        public struct Edge
        {
            public int From { get; set; }
            public int To { get; set; }
            public int Cost { get; set; }
            public Edge(int from, int to, int cost)
            {
                this.From = from;
                this.To = to;
                this.Cost = cost;
            }
        }
    }
    static Scanner sc = new Scanner();
}

class Scanner
{
    string[] S = new string[0];
    int Index = 0;
    char[] Separators = new char[] { ' ' };

    public string Next()
    {
        if (this.Index < this.S.Length) return this.S[this.Index++];
        var line = "";
        while (line == "") line = Console.ReadLine();
        this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries);
        if (this.S.Length == 0) return this.Next();
        this.Index = 0;
        return this.S[this.Index++];
    }
    public string ReadStr()
    {
        return this.Next();
    }
    public char ReadChar()
    {
        return this.Next()[0];
    }
    public int ReadInt()
    {
        return int.Parse(this.Next());
    }
    public uint ReadUInt()
    {
        return uint.Parse(this.Next());
    }
    public long ReadLong()
    {
        return long.Parse(this.Next());
    }
    public double ReadDouble()
    {
        return double.Parse(this.Next());
    }
    public Tuple<int, int> ReadTup(int add = 0)
    {
        return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add);
    }
    public Tuple<long, long> ReadTupLong(int add = 0)
    {
        return Tuple.Create(this.ReadLong() + add, this.ReadLong() + add);
    }
    public Tuple<int, int, int> ReadTup3(int add = 0)
    {
        return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add);
    }
    public Tuple<int, int, int, int> ReadTup4(int add = 0)
    {
        return Tuple.Create(this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add, this.ReadInt() + add);
    }
    public int[] ReadIntArray(int n)
    {
        var array = new int[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadInt();
        }
        return array;
    }
    public long[] ReadLongArray(int n)
    {
        var array = new long[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadLong();
        }
        return array;
    }
    public double[] ReadDoubleArray(int n)
    {
        var array = new double[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadDouble();
        }
        return array;
    }
    public char[] ReadCharArray(int n)
    {
        var array = new char[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadChar();
        }
        return array;
    }
    public string[] ReadStrArray(int n)
    {
        var array = new string[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadStr();
        }
        return array;
    }
    public Tuple<long, long>[] ReadTupLongArray(int n, int add = 0)
    {
        var array = new Tuple<long, long>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTupLong(add);
        }
        return array;
    }
    public Tuple<int, int>[] ReadTupArray(int n, int add = 0)
    {
        var array = new Tuple<int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup(add);
        }
        return array;
    }
    public Tuple<int, int, int>[] ReadTup3Array(int n, int add = 0)
    {
        var array = new Tuple<int, int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup3(add);
        }
        return array;
    }
    public Tuple<int, int, int, int>[] ReadTup4Array(int n, int add = 0)
    {
        var array = new Tuple<int, int, int, int>[n];
        for (int i = 0; i < n; i++)
        {
            array[i] = this.ReadTup4(add);
        }
        return array;
    }
}


Measured memory_bytes: 13396