#include "bits/stdc++.h"

using namespace std;
#ifdef _DEBUG
#define _GLIBCXX_DEBUG
#include "dump.hpp"
#else
#define dump(...)
#endif

#define int long long
#define ll long long
#define DBG 1
#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define rrep(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define loop(n) rep(loop, (0), (n))
#define all(c) begin(c), end(c)
const int INF = sizeof(int) == sizeof(long long) ? 0x3f3f3f3f3f3f3f3fLL : 0x3f3f3f3f;
const int MOD = (int)(1e9) + 7;
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
using pii = pair<int, int>;
// template<class T> ostream &operator<<(ostream &os,T &t){dump(t);return os;}
template <typename T, typename S>istream &operator>>(istream &is, pair<T, S> &p) { is >> p.first >> p.second; return is; }
//template <typename T, typename S>ostream &operator<<(ostream &os, pair<T, S> &p) {os << p.first << " " << p.second;return os;}

template <typename T> void printvv(const vector<vector<T>> &v) {
	cerr << endl;
	rep(i, 0, v.size()) rep(j, 0, v[i].size()) {
		if (typeid(v[i][j]).name() == typeid(INF).name() and v[i][j] == INF) {
			cerr << "INF";
		}
		else
			cerr << v[i][j];
		cerr << (j == v[i].size() - 1 ? '\n' : ' ');
	}
	cerr << endl;
}

#ifndef _DEBUG
#define printvv(...)
#endif
void YES(bool f) { cout << (f ? "YES" : "NO") << endl; }
void Yes(bool f) { cout << (f ? "Yes" : "No") << endl; }
template <class T, class U>bool chmin(T& a, U b) { if (a > b) { a = b; return true; }return false; }
template <class T, class U>bool chmax(T& a, U b) { if (a < b) { a = b; return true; }return false; }
//
//using Weight = int;
//using Flow = int;
//struct Edge {
//	int s, d; Weight w; Flow c; int id;
//	Edge() {};
//	Edge(int s, int d, Weight w = 1) : s(s), d(d), w(w), c(w) {};
//};
//bool operator<(const Edge &e1, const Edge &e2) { return e1.w < e2.w; }
//bool operator>(const Edge &e1, const Edge &e2) { return e2 < e1; }
//inline ostream &operator<<(ostream &os, const Edge &e) { return (os << '(' << e.s << ", " << e.d << ", " << e.w << ')'); }
//
//using Edges = vector<Edge>;
//using Graph = vector<Edges>;
//using Array = vector<Weight>;
//using Matrix = vector<Array>;
//
//void addArc(Graph &g, int s, int d, Weight w = 1) {
//	g[s].emplace_back(s, d, w);
//}
//void addEdge(Graph &g, int a, int b, Weight w = 1) {
//	addArc(g, a, b, w);
//	addArc(g, b, a, w);
//}
////単一始点最短経路(負閉路あり)
////Bellman-Ford O(|V||E|)
////dist: 始点から各頂点までの最短距離
////戻り値: 最短経路木の親頂点, 負閉路なし:true あり:false
//pair<vector<int>, bool> bellmanFord(const Graph &g, int s, Array &dist) {
//	int n = g.size();
//	vector<int> prev(n, -1);
//	Edges es; for (int i = 0; i < n; i++) for (auto &e : g[i]) es.emplace_back(e);
//	dist.assign(n, INF); dist[s] = 0;
//	bool negative_cycle = false;
//	for (int i = 0;; i++) {
//		bool update = false;
//		for (auto &e : es) {
//			if (dist[e.s] != INF && dist[e.d] > dist[e.s] + e.w) {
//				dist[e.d] = dist[e.s] + e.w;
//				prev[e.d] = e.s;
//				update = true;
//			}
//		}
//		if (!update) break;
//		if (i > n) { negative_cycle = true; break; }
//	}
//	return make_pair(prev, !negative_cycle);
//}
//
//signed main(signed argc, char *argv[]) {
//	cin.tie(0);
//	ios::sync_with_stdio(false);
//	cout << fixed << setprecision(12);
//
//	int N, M; cin >> N >> M;
//	int P; cin >> P;
//
//	Graph g(N);
//	Array dist(N);
//	loop(M) {
//		int a, b, c; cin >> a >> b >> c;
//		a--, b--;
//		addArc(g, a, b, P - c);
//	}
//	auto ans = bellmanFord(g, 0, dist);
//
//	if (not ans.second) {
//		dump("inf");
//		cout << -1 << endl;
//	}
//	else {
//		cout << -dist[N - 1] << endl;
//	}
//
//	return 0;
//}

struct Edge {
	int from, to, cost;
	Edge() {}
	Edge(int from, int to, int cost) :from(from), to(to), cost(cost) {}
};

signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, M; cin >> N >> M;
	int P; cin >> P;
	vector<Edge>edges(M);
	rep(i, 0, M) {
		int a, b, c; cin >> a >> b >> c;
		a--, b--;
		edges[i].from = a;
		edges[i].to = b;
		edges[i].cost = P - c;
	}
	vector<int>d(N, INF);
	d[0] = 0;
	rep(i, 0, N - 1) {
		rep(j, 0, M) {
			Edge e(edges[j]);
			if (d[e.from] == INF)continue;
			if (d[e.to] > d[e.from] + e.cost) {
				d[e.to] = d[e.from] + e.cost;
			}
		}
	}
	int ans = -d[N - 1];

	vector<int>neg(N, 0);
	rep(i, 0, N) {
		rep(j, 0, M) {
			Edge e(edges[j]);
			if (d[e.from] == INF)continue;
			if (d[e.to] > d[e.from] + e.cost) {
				d[e.to] = d[e.from] + e.cost;
				neg[e.to] = neg[e.from] = 1;
			}

			if (neg[e.from])neg[e.to] = 1;
		}
	}
	if (neg[N - 1])cout << -1 << endl;
	else cout << max(0ll, ans) << endl;
	return 0;
}

Measured memory_bytes: 384