using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using SB = System.Text.StringBuilder;
//using System.Threading.Tasks;
//using System.Text.RegularExpressions;
//using System.Globalization;
//using System.Diagnostics;
using static System.Console;
using System.Numerics;
using static System.Math;
using pair = Pair<int, int>;

class Program
{
    static void Main()
    {
        //SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    readonly Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 }; //→↓←↑
    readonly int mod = 1000000007;
    readonly int dom = 998244353;
    bool chmax<T>(ref T a, T b) where T : IComparable<T> { if (a.CompareTo(b) < 0) { a = b; return true; } return false; }
    bool chmin<T>(ref T a, T b) where T : IComparable<T> { if (b.CompareTo(a) < 0) { a = b; return true; } return false; }

    void solve()
    {
        int N = cin.nextint;
        int M = cin.nextint;
        int P = cin.nextint;
        var BF = new BellmanFord();
        var G = BF.Input(P, M, true);

        var dist = new long[N];
        var ok = BF.Run(G, 0, N, out dist);

        if (ok)
        {
            WriteLine("-1");
        }
        else
        {
            WriteLine(Max(0, -dist[N - 1]));
        }
    }

}

class BellmanFord
{
    public readonly long Inf;
    public BellmanFord(long Inf = long.MaxValue / 2) { this.Inf = Inf; }

    public class Edge
    {
        public int from, to; public long cost;
        public Edge(int from, int to, long cost)
        {
            this.from = from;
            this.to = to;
            this.cost = cost;
        }
    }
    /// <summary>
    /// BellmanFordな入力を行う
    /// </summary>
    /// <param name="m">辺数</param>
    /// <param name="dir">有向/無向 デフォルト: 無向</param>
    /// <param name="indexed">indexedの補正 デフォルト: 1</param>
    /// <returns></returns>
    public Edge[] Input(int P, int m, bool dir = false, int indexed = 1, bool cost = true)
    {
        var cin = new Scanner();
        var ret = new Edge[dir ? m : m + m];
        for (int i = 0; i < m; i++)
        {
            int a = cin.nextint - indexed;
            int b = cin.nextint - indexed;
            var c = cost ? cin.nextlong : 1;
            c = P - c;
            ret[i] = new Edge(a, b, c);
            if (!dir) ret[i + m] = new Edge(b, a, c);
        }
        return ret;
    }
    public bool Run(Edge[] edges, int s, int n, out long[] dist)
    {
        dist = new long[n];
        for (int i = 0; i < n; i++) dist[i] = Inf;
        dist[s] = 0;
        for (int i = 0; i <= 4 * n; i++)
        {
            foreach (var e in edges)
            {
                if (dist[e.from] == Inf) continue;
                var d = dist[e.from] + e.cost;
                if (d < dist[e.to])
                {
                    dist[e.to] = d;

                    // n回目にも更新があるなら負の閉路が存在する
                    if (n - 1 <= i && e.to == n - 1) return true;
                }
            }
        }
        return false;
    }
}


static class Ex
{
    public static void join<T>(this IEnumerable<T> values, string sep = " ") => WriteLine(string.Join(sep, values));
    public static string concat<T>(this IEnumerable<T> values) => string.Concat(values);
    public static string reverse(this string s) { var t = s.ToCharArray(); Array.Reverse(t); return t.concat(); }

    public static int lower_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) < 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
    public static int upper_bound<T>(this IList<T> arr, T val) where T : IComparable<T>
    {
        int low = 0, high = arr.Count;
        int mid;
        while (low < high)
        {
            mid = ((high - low) >> 1) + low;
            if (arr[mid].CompareTo(val) <= 0) low = mid + 1;
            else high = mid;
        }
        return low;
    }
}

class Pair<T, U> : IComparable<Pair<T, U>> where T : IComparable<T> where U : IComparable<U>
{
    public T f; public U s;
    public Pair(T f, U s) { this.f = f; this.s = s; }
    public int CompareTo(Pair<T, U> a) => f.CompareTo(a.f) != 0 ? f.CompareTo(a.f) : s.CompareTo(a.s);
    public override string ToString() => $"{f} {s}";
}

class Scanner
{
    string[] s; int i;
    readonly char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan => ReadLine().Split();
    public int[] scanint => Array.ConvertAll(scan, int.Parse);
    public long[] scanlong => Array.ConvertAll(scan, long.Parse);
    public double[] scandouble => Array.ConvertAll(scan, double.Parse);
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint => int.Parse(next);
    public long nextlong => long.Parse(next);
    public double nextdouble => double.Parse(next);
}


Measured memory_bytes: 13308