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

public class Contest
{
	public static void Main()
	{
        int n,m;
		VT<int,int,int>[] abcl;
		MyIO.ReadMulti(out n, out m);
		MyIO.ReadLines(m, out abcl);
 
		List<VT<int,int,int>> g = new List<VT<int, int, int>>();
		foreach(var s in abcl){
			g.Add(new VT<int, int, int>(s.Item1-1,s.Item2-1,-s.Item3));
		}

		long[] r = BellmanFord(g.ToArray(), n, 0);
		if(r[n-1]==long.MinValue){
			MyIO.WriteMulti("inf");
		}else{
			MyIO.WriteMulti(-r[n-1]);
		}
 

	}




	public static long[] BellmanFord(VT<int,int,int>[] inEdges, int V, int start) {
		long[] dist = Enumerable.Repeat(long.MaxValue, V).ToArray();
		dist[start] = 0;
		for(int i = 0; i < V - 1; i++) {
			foreach(var e in inEdges) {
				if(dist[e.Item1] == long.MaxValue) continue;
				dist[e.Item2] = Math.Min(dist[e.Item2], dist[e.Item1] + e.Item3);
			}
		}
		bool[] negative = new bool[V];
		for(int i = 0; i < V ; i++) {
			foreach(var e in inEdges) {
				if(dist[e.Item1] == long.MaxValue) continue;
				if(dist[e.Item1] + e.Item3 < dist[e.Item2]) {
					dist[e.Item2] = dist[e.Item1] + e.Item3;
					negative[e.Item2] = true;
				}
				if(negative[e.Item1]) negative[e.Item2] = true;
			}
		}
		for(int i = 0; i < V ; i++) {
			if(negative[i]) dist[i] = long.MinValue;
		}
		return dist;
	}

}


public class UnionFind {
    private int[] data;

    public UnionFind(int size) {
        data = new int[size];
        for (int i = 0; i < size; i++) data[i] = -1;
    }

    public bool Unite(int x, int y) {
        x = Find(x);
        y = Find(y);

        if (x != y) {
            if (data[y] < data[x]) {
                var tmp = y;
                y = x;
                x = tmp;
            }
            data[x] += data[y];
            data[y] = x;
        }
        return x != y;
    }

    public bool IsSameGroup(int x, int y) { return Find(x) == Find(y); }

    public int Find(int x) { return data[x] < 0 ? x : data[x] = Find(data[x]); }

    public int Size(int x) { return -data[Find(x)]; }

}



public struct VT<T, U>
{
	public T Item1; public U Item2;
    public VT(T a, U b) { Item1 = a; Item2 = b; }
}
public struct VT<T, U, V>
{
	public T Item1; public U Item2; public V Item3;
    public VT(T a, U b, V c) { Item1 = a; Item2 = b; Item3 = c; }
}
public struct VT<T, U, V, W>
{
	public T Item1; public U Item2; public V Item3; public W Item4;
    public VT(T a, U b, V c, W d) { Item1 = a; Item2 = b; Item3 = c; Item4 = d; }
}

public class Printer : System.IO.StreamWriter
{
	public override IFormatProvider FormatProvider { get { return System.Globalization.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 static class MyIO
{
	private static char[] splitter = new char[] {' '};
	private static bool eq<T, U>() => typeof(T).Equals(typeof(U));
	private static T ct<T, U>(U a) => (T)Convert.ChangeType(a, typeof(T));
	private static T cv<T>(string s) => eq<T, int>()    ? ct<T, int>(int.Parse(s))
	                                  : eq<T, long>()   ? ct<T, long>(long.Parse(s))
	                                  : eq<T, double>() ? ct<T, double>(double.Parse(s, System.Globalization.CultureInfo.InvariantCulture))
	                                  : eq<T, char>()   ? ct<T, char>(s[0])
	                                                    : ct<T, string>(s);				
	public static string[] ReadMulti<T>(out T a) {
		var ar = Console.ReadLine().Split(splitter, StringSplitOptions.RemoveEmptyEntries); 
		a = cv<T>(ar[0]);
		return ar;
	}
	public static string[] ReadMulti<T, U>(out T a, out U b) {
		var ar = ReadMulti<T>(out a); 
        b = cv<U>(ar[1]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V>(out T a, out U b, out V c) {
		var ar = ReadMulti<T, U>(out a, out b); 
        c = cv<V>(ar[2]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W>(out T a, out U b, out V c, out W d) {
		var ar = ReadMulti<T, U, V>(out a, out b, out c); 
        d = cv<W>(ar[3]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W, X>(out T a, out U b, out V c, out W d, out X e) {
		var ar = ReadMulti<T, U, V, W>(out a, out b, out c, out d); 
        e = cv<X>(ar[4]);
		return ar;
	}
	public static string[] ReadMulti<T, U, V, W, X, Y>(out T a, out U b, out V c, out W d, out X e, out Y f) {
		var ar = ReadMulti<T, U, V, W, X>(out a, out b, out c, out d, out e); 
        f = cv<Y>(ar[5]);
		return ar;
	}
	public static string[] ReadArray<T>(out T[] a) {		
		var ar = Console.ReadLine().Split(splitter, StringSplitOptions.RemoveEmptyEntries);
		a = ar.Select(cv<T>).ToArray();
		return ar;
	}		
	public static string[][] ReadLines<T>(int n, out T[] a) {
		a = new T[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) arr[i] = ReadMulti(out a[i]);
		return arr;
	}
	public static string[][] ReadLines<T, U>(int n, out VT<T, U>[] a) {
		a = new VT<T, U>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p;
			arr[i] = ReadMulti(out o, out p);
			a[i] = new VT<T, U>(o, p);
		}
		return arr;
	}
	public static string[][] ReadLines<T, U, V>(int n, out VT<T, U, V>[] a) {
		a = new VT<T, U, V>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p; V q;
			arr[i] = ReadMulti(out o, out p, out q);
			a[i] = new VT<T, U, V>(o, p, q);
		}
		return arr;
	}
	public static string[][] ReadLines<T, U, V, W>(int n, out VT<T, U, V, W>[] a) {
		a = new VT<T, U, V, W>[n];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) {
			T o; U p; V q; W r;
			arr[i] = ReadMulti(out o, out p, out q, out r);
			a[i] = new VT<T, U, V, W>(o, p, q, r);
		}
		return arr;
	}
	public static string[][] ReadMatrix<T>(int n, out T[][] a) {
		a = new T[n][];
		string[][] arr = new string[n][];
		for(int i=0; i<n; i++) arr[i] = ReadArray(out a[i]);
		return arr;
	}

	private static void wwp(Action act){
		var sw = new Printer(Console.OpenStandardOutput()){AutoFlush = false};
		Console.SetOut(sw);
		act();
		Console.Out.Flush();
		sw.AutoFlush = true;
		Console.SetOut(sw);
	}
	public static void WriteMulti(params object[] a) {
		wwp(()=>{
			foreach(object x in a) Console.Write("{0} ", x);
			Console.WriteLine();
		});
	}
	public static void WriteArray<T>(T[] a) {
		wwp(()=>{
			foreach(T x in a) Console.Write("{0} ", x);
			Console.WriteLine();
		});
	}
	public static void WriteLines<T>(T[] a) {
		wwp(()=>{
			foreach(T x in a) Console.WriteLine(x);
		});
	}



}





Measured memory_bytes: 13544