using System;
using System.Collections.Generic;
using static Assistant.Input;
using static Assistant.Debug;
using System.Linq;
using Assistant;

namespace ABC137E_2
{
    class Program
    {
        static void Main(string[] args)
        {
            var N = RInt;
            var M = RInt;
            var P = RInt;

            BellmanFord bf = new BellmanFord(N);
            for (int i = 0; i < M; i++)
            {
                var a = RInt - 1;
                var b = RInt - 1;
                var c = RInt;
                bf.AddEdge(a, b, P - c);
            }

            bool[] negative;
            var ans = bf.Start(0, out negative);

            if (!negative[N - 1]) Console.WriteLine(Math.Max(-ans[N - 1], 0));
            else Console.WriteLine(-1);
        }


    }

    /// <summary>
    /// 単一始点最短経路 負の辺に対応 O(VE)
    /// </summary>
    class BellmanFord
    {
        public long BIG = long.MaxValue / 2;
        List<int> _start;
        List<int> _to;
        List<long> _cost;
        int _v;
        int _e;
        public BellmanFord(int V)
        {
            _v = V;
            _start = new List<int>();
            _to = new List<int>();
            _cost = new List<long>();
        }

        public void AddEdge(int from, int to, long cost)
        {
            _start.Add(from);
            _to.Add(to);
            _cost.Add(cost);
            _e = _start.Count;
        }

        public long[] Start(int start, out bool[] negativeCycles)
        {
            //初期化・開始点の設定
            long[] cost = new long[_v];
            for (int i = 0; i < _v; i++)
            {
                cost[i] = BIG;
            }
            cost[start] = 0;

            //メインループ
            negativeCycles = new bool[_v];
            for (int i = 0; i < 2 * _v; i++)
            {
                for (int e = 0; e < _e; e++) // 辺に関するループ
                {
                    int f = _start[e];
                    int t = _to[e];
                    long c = _cost[e];

                    if (cost[f] > BIG / 2) continue;

                    if (i <= _v - 1)
                    {
                        long cand = cost[f] + c;
                        if (cand < cost[t])  // 更新条件
                        {
                            cost[t] = cand;

                            if (i == _v - 1)
                            {
                                negativeCycles[t] = true;
                            }
                        }
                    }
                    else if (negativeCycles[f]) negativeCycles[t] = true;
                }
            }
            for (int i = 0; i < _v; i++)
            {
                if (negativeCycles[i]) cost[i] = long.MaxValue;
            }

            return cost;
        }
    }
}

namespace Assistant
{
    static class Input
    {
        static List<string> line = new List<string>();
        static int index = 0;
        static String RNext()
        {
            if (line.Count <= index) line.AddRange(Console.ReadLine().Split());
            return line[index++];
        }
        public static int RInt => int.Parse(RNext());
        public static long RLong => long.Parse(RNext());
        public static int[] RInts => Console.ReadLine().Split().Select(int.Parse).ToArray();
        public static long[] RLongs => Console.ReadLine().Split().Select(long.Parse).ToArray();
        public static string RString => RNext();
        //以下未テスト
        public static int[] RIntsC(int c) => Enumerable.Repeat(0, c).Select(x => int.Parse(RNext())).ToArray();
        public static long[] RLongsC(int c) => Enumerable.Repeat(0, c).Select(x => long.Parse(RNext())).ToArray();
        public static char[][] RMap(int h) => Enumerable.Repeat(0, h).Select(x => Console.ReadLine().ToCharArray()).ToArray();
    }

    static class Debug
    {
        static public void Draw2D<T>(T[,] map, int mode = 1)
        {
#if DEBUG
            int W = map.GetLength(0);
            int H = map.GetLength(1);

            string[,] map2 = new string[W + 1, H + 1];
            for (int i = 0; i < W + 1; i++)
            {
                for (int j = 0; j < H + 1; j++)
                {
                    if (i == 0 && j == 0) map2[i, j] = 0.ToString();
                    else if (i == 0) map2[i, j] = (j - 1).ToString();
                    else if (j == 0) map2[i, j] = (i - 1).ToString();
                    else map2[i, j] = map[i - 1, j - 1].ToString();
                }
            }

            for (int i = 0; i < W + 1; i++)
            {
                for (int j = 0; j < H + 1; j++)
                {
                    if (mode == 0) Console.Write(map2[i, j].Last());
                    if (mode == 1) Console.Write(map2[i, j] + " ");
                }
                Console.WriteLine();
            }
            Console.WriteLine();
#endif
        }

        public static void Draw1D<T>(T[] array, int mode = 0)
        {
#if DEBUG
            Console.WriteLine(string.Join(" ", array));
#endif
        }
    }
}


Measured memory_bytes: 14292