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

namespace Contest
{
    struct Edge
    {
        public int From, To, Cost;

        public Edge(int f, int t, int c)
        {
            From = f;
            To = t;
            Cost = c;
        }
    }

    class Program
    {
        private Scanner sc;
        private int N, M, P;
        private int[] A, B, C;
        public void Solve()
        {
            sc = new Scanner();
            N = sc.NextInt();
            M = sc.NextInt();
            P = sc.NextInt();
            A = new int[M];
            B = new int[M];
            C = new int[M];
            for (int i = 0; i < M; i++)
            {
                A[i] = sc.NextInt() - 1;
                B[i] = sc.NextInt() - 1;
                C[i] = sc.NextInt();
            }
            var edges = new List<Edge>[N];
            for (int i = 0; i < N; i++)
            {
                edges[i] = new List<Edge>();
            }

            for (int i = 0; i < M; i++)
            {
                edges[A[i]].Add(new Edge(A[i], B[i], C[i] - 1));
            }

            var cost = new long[N];
            for (int i = 0; i < N; i++)
            {
                cost[i] = int.MinValue;
            }

            cost[0] = 0;

            for (int i = 0; i < N; i++)
            {
                for (int j = 0; j < M; j++)
                {
                    cost[B[j]] = Math.Max(cost[B[j]], cost[A[j]] + C[j] -P);
                }
            }

            var ans = cost[N - 1];

            for (int i = 0; i < N; i++)
            {
                for (int j = 0; j < M; j++)
                {
                    cost[B[j]] = Math.Max(cost[B[j]], cost[A[j]] + C[j] - P);
                }
            }

            Console.WriteLine(cost[N - 1] == ans ? Math.Max(0,ans):-1);
        }

        static void Main() => new Program().Solve();
    }
}

class Scanner
{
    public Scanner()
    {
        _stream = new StreamReader(Console.OpenStandardInput());
        _pos = 0;
        _line = new string[0];
        _separator = ' ';
    }
    private readonly char _separator;
    private readonly StreamReader _stream;
    private int _pos;
    private string[] _line;
    #region get a element
    public string Next()
    {
        if (_pos >= _line.Length)
        {
            _line = _stream.ReadLine().Split(_separator);
            _pos = 0;
        }
        return _line[_pos++];
    }
    public int NextInt()
    {
        return int.Parse(Next());
    }
    public long NextLong()
    {
        return long.Parse(Next());
    }
    public double NextDouble()
    {
        return double.Parse(Next());
    }
    #endregion
    #region convert array
    private int[] ToIntArray(string[] array)
    {
        var result = new int[array.Length];
        for (int i = 0; i < array.Length; i++)
        {
            result[i] = int.Parse(array[i]);
        }

        return result;
    }
    private long[] ToLongArray(string[] array)
    {
        var result = new long[array.Length];
        for (int i = 0; i < array.Length; i++)
        {
            result[i] = long.Parse(array[i]);
        }

        return result;
    }
    private double[] ToDoubleArray(string[] array)
    {
        var result = new double[array.Length];
        for (int i = 0; i < array.Length; i++)
        {
            result[i] = double.Parse(array[i]);
        }

        return result;
    }
    #endregion
    #region get array
    public string[] Array()
    {
        if (_pos >= _line.Length)
            _line = _stream.ReadLine().Split(_separator);
        _pos = _line.Length;
        return _line;
    }
    public int[] IntArray()
    {
        return ToIntArray(Array());
    }
    public long[] LongArray()
    {
        return ToLongArray(Array());
    }
    public double[] DoubleArray()
    {
        return ToDoubleArray(Array());
    }
    #endregion
}

Measured memory_bytes: 13268