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; 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(ref T a, T b) where T : IComparable { if (a.CompareTo(b) < 0) { a = b; return true; } return false; } bool chmin(ref T a, T b) where T : IComparable { if (b.CompareTo(a) < 0) { a = b; return true; } return false; } class Edge : IComparable { public int from, to, id; public long cost; public Edge(int from, int to, long cost, int id = -1) { this.from = from; this.to = to; this.cost = cost; this.id = id; } public int CompareTo(Edge e) => cost.CompareTo(e.cost); } void solve() { int N = cin.nextint; int M = cin.nextint; var A = cin.nextlong; var E = new Edge[M]; for (int i = 0; i < M; i++) { E[i] = new Edge(cin.nextint - 1, cin.nextint, cin.nextlong); } E = E.OrderBy(i => i.to).ThenBy(i => i.from).ToArray(); var dp = new long[N + 1]; var S = new SegTree(N + 1, Max, 0); foreach (var e in E) { int L = e.from; int R = e.to; long P = e.cost; if (R == N) { chmax(ref dp[R], S[0, L] - A + P); if(dp[L] > 0) chmax(ref dp[R], dp[L] + P); } else if (L == 0) { chmax(ref dp[R], P - A); } else { chmax(ref dp[R], S[0, L] - 2 * A + P); if (dp[L] > 0) chmax(ref dp[R], dp[L] - A + P); } S.Update(R, dp[R]); //WriteLine(); //dp.join(); //S.Items.join(); //WriteLine(); } WriteLine(S[0, N]); } } /// riantkb class SegTree { readonly int n; int s, t; T[] tr; readonly Func f; readonly T exnum; /// /// セグメントツリーの構築1 /// /// 要素数 /// マージ関数 /// 単位元 public SegTree(int m, Func f, T ex) { this.f = f; exnum = ex; n = 1; while (n < m) n <<= 1; tr = new T[(n << 1) - 1]; for (int i = 0; i < tr.Length; i++) tr[i] = ex; } public SegTree(int m, Func f, T ex, T ini) : this(m, f, ex) { for (int i = 0; i < m; i++) Assign(i, ini); All_Update(); } public SegTree(int m, Func f, T ex, IList ini) : this(m, f, ex) { for (int i = 0; i < m; i++) Assign(i, ini[i]); All_Update(); } public T Look(int j) => tr[j + n - 1]; public T Peek() => tr[0]; /// /// 最下層に値の代入 /// /// 代入するインデックス /// 代入する値 public void Assign(int j, T x) => tr[j + n - 1] = x; public void Update(int j, T x) { Assign(j, x); Update(j); } public void Update(int j) { int i = j + n - 1; while (i > 0) { i = i - 1 >> 1; tr[i] = f(tr[i << 1 | 1], tr[i + 1 << 1]); } } public void All_Update() { for (int i = n - 2; i >= 0; i--) tr[i] = f(tr[i << 1 | 1], tr[i + 1 << 1]); } /// /// return node[s, t] 区間クエリ /// /// 左端 0-indexed /// 右端 0-indexed /// node[s, t] public T this[int s, int t] => Run(s, t); T Run(int s, int t) { t++; this.s = s; this.t = t; return Query(0, 0, n); } T Query(int k, int l, int r) => r <= s || t <= l ? exnum : s <= l && r <= t ? tr[k] : f(Query(k << 1 | 1, l, l + r >> 1), Query(k + 1 << 1, l + r >> 1, r)); public T[] Items { get { var ret = new T[n]; for (int i = 0; i < ret.Length; i++) { ret[i] = Run(i, i); } return ret; } } } static class Ex { public static void join(this IEnumerable values, string sep = " ") => WriteLine(string.Join(sep, values)); public static string concat(this IEnumerable 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(this IList arr, T val) where T : IComparable { 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(this IList arr, T val) where T : IComparable { 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 : IComparable> where T : IComparable where U : IComparable { public T f; public U s; public Pair(T f, U s) { this.f = f; this.s = s; } public int CompareTo(Pair 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); }