#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
inline ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
inline ll lcm(ll a, ll b) { return a / gcd(a, b)*b; }
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T>& V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> >& Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T>& mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }
template<typename T>vector<T> make_v(size_t a){return vector<T>(a);}
template<typename T,typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type fill_v(T &t,const V &v){t=v;}
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type fill_v(T &t,const V &v){for(auto &e:t) fill_v(e,v);}
/*
 <url:>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */

class Bellman_ford {
public:
    struct edge {
        ll u;
        ll v;
        ll cost;
        edge() {}
        edge(ll u, ll v, ll c) :u(u), v(v), cost(c) {}
    };
    
    ll V;
    vector<vector<edge> > G;
    vector<ll> dist;
    Bellman_ford(ll V) :V(V) {
        G.resize(V);
    }
    
    void add_edge(ll u, ll v, ll cost, bool undirected = false) {
        G[u].push_back(edge(u, v, cost));
        if (undirected) {
            G[v].push_back(edge(v, u, cost));
        }
    }
    
    bool calc_dist(ll s,vector<int>& visitO,vector<int>& visitN) {
        dist.assign(V,LINF);
        dist[s] = 0;
        
        for (int i = 0; i < V;i++) {
            bool updated = true;
            for (int v = 0; v < V;v++) {
                for (int j = 0; j < (int)G[v].size();j++){
                    edge& e = G[v][j];
                    if (dist[e.v] > dist[v] + e.cost) {
                        if(visitO[e.v] && visitN[e.v]){
                            dist[e.v] = dist[v] + e.cost;
                            updated = false;
                            if (i == V - 1) return true; // 負閉路
                        }
                    }
                }
            }
            if(updated) return false;
        }
        return false;
    }
    
    inline ll get_dist(ll v) const { return dist[v]; }
};

template<class Type>
Type solve(Type res = Type()){
    ll N,M,P; cin >> N >> M >> P;
    Bellman_ford BF(N);
    vector<vector<ll>> G(N),rG(N);
    for(int i = 0; i < M;i++){
        ll a,b,c; cin >> a >> b >> c;
        a--; b--;
        BF.add_edge(a, b,P-c);
        
        G[a].push_back(b);
        rG[b].push_back(a);
    }
    
    vector<int> visitO(N),visitN(N);
    function<void(ll,bool)> rec = [&](ll n,bool rev = false){
        if(!rev){
            if(visitO[n]) return;
            visitO[n] = true;
            for(auto next:G[n]){
                rec(next,rev);
            }
        }else{
            if(visitN[n]) return;
            visitN[n] = true;
            for(auto next:rG[n]){
                rec(next,rev);
            }
        }
    };
    rec(0,false);
    rec(N-1,true);
    
    bool ok = BF.calc_dist(0,visitO,visitN);
    if(ok) return -1;
    else return max(0LL,-BF.get_dist(N-1));
    
    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    // solve(0);
    cout << fixed << setprecision(15) << solve<ll>() << endl;
    return 0;
}


Measured memory_bytes: 896