#include <bits/stdc++.h>
#include <boost/multiprecision/cpp_int.hpp>
using namespace std;

//#define int long long
//using ll = boost::multiprecision::cpp_int;
using ll = long long;
//constexpr int INF = 1e9;//INT_MAX=(1<<31)-1=2147483647
constexpr ll INF = (ll)1e18;//(1LL<<63)-1=9223372036854775807
constexpr ll MOD = (ll)1e9 + 7;
constexpr double EPS = 1e-9;
constexpr int dx[4]={1,0,-1,0};
constexpr int dy[4]={0,1,0,-1};
#ifdef LOCAL_ENV
	#define debug(var) std::cout<<#var" = "<<var<<std::endl
#else
	#define debug(var)
#endif
#define p(var) std::cout<<var<<std::endl
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define all(a) (a).begin(), (a).end()
#define PI (acos(-1))
template<typename T> inline T power(T x, T n){ return n ? power(x*x%MOD,n/2)*(n%2?x:1)%MOD : 1; }
template<typename T> inline T gcd(T a, T b) { return b ? gcd(b,a%b) : a; }
template<typename T> inline T lcm(T a, T b) { return a / gcd(a,  b) * b; }
template<typename T1, typename T2>inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template<typename T1, typename T2>inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }
template<typename T1, typename T2> ostream& operator<<(ostream& s, const pair<T1, T2>& p) {return s << "(" << p.first << ", " << p.second << ")";}
template<typename T> ostream& operator<<(ostream& s, const vector<T>& v) {
	for (int i = 0, len = v.size(); i < len; ++i){
		s << v[i]; if (i < len - 1) s << "\t";
	}
	return s;
}
template<typename T> ostream& operator<<(ostream& s, const vector< vector<T> >& vv) {
	for (int i = 0, len = vv.size(); i < len; ++i){
		s << vv[i] << endl;
	}
	return s;
}
template<typename T1, typename T2> ostream& operator<<(ostream& s, const map<T1, T2>& m) {
	s << "{" << endl;
	for (typeof(m.begin()) itr = m.begin(); itr != m.end(); ++itr){
		s << "\t" << (*itr).first << " : " << (*itr).second << endl;
	}
	s << "}" << endl;
	return s;
}

/*-----8<-----8<-----*/


class Edge {
public:
	ll from,to,cost;
	Edge() {}
	Edge(ll from, ll to, ll cost) : from(from), to(to), cost(cost) {}
};

/*
引数
　g:探索するグラフ
　start:探索するスタートノード番号
戻り値
　dist:スタートノードから各頂点までの距離
　prev:最短路木の親頂点
　return: 負閉路が存在するとき true，負閉路が存在しない(グラフが正常)のとき false
*/
bool bellman_ford(const vector<vector<Edge>> &g, ll start, vector<ll> &dist, vector<ll> &prev) {
	ll gsize = g.size();
	dist.assign(gsize, INF+INF); dist[start] = 0;
	prev.assign(gsize, -1);
	vector<ll> dist_phase1,dist_phase2;

	for(ll k=0; k<2*gsize; k++){
		for(ll i=0; i<gsize; i++){
			for(Edge e : g[i]) {
				if (dist[e.to] > dist[e.from] + e.cost) {
					dist[e.to] = dist[e.from] + e.cost;
					prev[e.to] = e.from;
				}
			}
		}
		if (k == gsize-1) dist_phase1 = dist;
		else if (k == 2*gsize-1) dist_phase2 = dist;
	}

	bool negative_cycle = false;
	for(ll i=0; i<gsize; i++){
		if (dist_phase1[i] != dist_phase2[i]) {
			negative_cycle = true;
			dist[i] = -INF;
		}
	}

	return negative_cycle;
}



signed main() {

	ll N, M, P;
	cin >> N >> M >> P;
	vector<vector<Edge>> g(N,vector<Edge>());
	for (ll i=0; i<M; i++) {
		ll from,to,cost;
		cin >> from >> to >> cost;
		from--;to--;
		Edge e1=Edge(from,to,P-cost);
		g[e1.from].push_back(e1);
	}

	vector<ll> dist, prev;
	bool negativecycle=bellman_ford(g, 0, dist, prev);
	debug(dist);
	if(negativecycle && dist[N-1]==-INF){
		p(-1);
		return 0;
	}

	ll ans=-dist[N-1]<0 ? 0 : -dist[N-1];
	p(ans);

	return 0;
}


Measured memory_bytes: 640