#include <bits/stdc++.h>
#define GET_MACRO(_1,_2,_3,_4,_5,_6,_7,_8,NAME,...) NAME
#define pr(...) cerr<< GET_MACRO(__VA_ARGS__,pr8,pr7,pr6,pr5,pr4,pr3,pr2,pr1)(__VA_ARGS__) <<endl
#define pr1(a) (#a)<<"="<<(a)<<" "
#define pr2(a,b) pr1(a)<<pr1(b)
#define pr3(a,b,c) pr1(a)<<pr2(b,c)
#define pr4(a,b,c,d) pr1(a)<<pr3(b,c,d)
#define pr5(a,b,c,d,e) pr1(a)<<pr4(b,c,d,e)
#define pr6(a,b,c,d,e,f) pr1(a)<<pr5(b,c,d,e,f)
#define pr7(a,b,c,d,e,f,g) pr1(a)<<pr6(b,c,d,e,f,g)
#define pr8(a,b,c,d,e,f,g,h) pr1(a)<<pr7(b,c,d,e,f,g,h)
#define prArr(a) {cerr<<(#a)<<"={";int i=0;for(auto t:(a))cerr<<(i++?", ":"")<<t;cerr<<"}"<<endl;}
using namespace std;
using Int = long long;
using _int = int;
using ll = long long;
using Double = long double;
const Int INF = (1LL<<60)+1e9; // ~ 1.15 * 1e18
const Int mod = (1e9)+7;
const Double EPS = 1e-8;
const Double PI = 6.0 * asin((Double)0.5);
using P = pair<Int,Int>;
template<class T> T Max(T &a,T b){return a=max(a,b);}
template<class T> T Min(T &a,T b){return a=min(a,b);}
template<class T1, class T2> ostream& operator<<(ostream& o,pair<T1,T2> p){return o<<"("<<p.first<<","<<p.second<<")";}
template<class T1, class T2, class T3> ostream& operator<<(ostream& o,tuple<T1,T2,T3> t){
  return o<<"("<<get<0>(t)<<","<<get<1>(t)<<","<<get<2>(t)<<")";}
template<class T1, class T2> istream& operator>>(istream& i,pair<T1,T2> &p){return i>>p.first>>p.second;}
template<class T> ostream& operator<<(ostream& o,vector<T> a){Int i=0;for(T t:a)o<<(i++?" ":"")<<t;return o;}
template<class T> istream& operator>>(istream& i,vector<T> &a){for(T &t:a)i>>t;return i;}
//INSERT ABOVE HERE

template<typename ctype>
class BellmanFord{
public:
  double EPS = 1e-8;
  using T = tuple<int, int, ctype>;
  int V;
  ctype INF;
  vector<T> edge;
  BellmanFord():V(-1){}
  BellmanFord(int V, ctype INF):V(V), INF(INF){}

  void add_edge(int from, int to,ctype cost){
    assert(0 <= from && from < V);
    assert(0 <= to && to < V);
    edge.push_back(T(from, to, cost));
  }

  void add_bidirectional_edge(int a,int b,ctype cost){
    add_edge(a, b, cost);
    add_edge(b, a, cost);
  }

  //s番目の頂点から各頂点への最短距離を求める。
  pair<vector<ctype>, vector<int> > calcD(int start, vector<Int> D2={}){
    assert(0 <= start && start < V);
    vector<ctype> D(V, INF);   //最短距離
    D[start] = 0;

    int cnt2 = 0;
    bool update = true;
    vector<int> updated(V, 0);
    while(update){
      if(cnt2++ > 10 * V) return make_pair(vector<Int>(), vector<int>());
      update = false;
      vector<int> flag(V, 0);
      for(auto e:edge){
        int from, to;
        ctype cost;
        tie(from, to, cost) = e;
        ctype ncost = D[from] + cost;
        if(ncost >= D[to] || D[from] == INF || (!D2.empty() && D2[to] == INF)) continue;
        D[to] = ncost;
        flag[to] = 1;
        update = true;
      }
      for(int i=0;i<V;i++) updated[i] += flag[i];
    }
    return make_pair(D, updated);
  }
};


signed main(){
  srand((unsigned)time(NULL));
  cin.tie(0);
  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(12);

  int N, M, P;
  cin>>N>>M>>P;
  BellmanFord<Int> belman(N, INF);
  BellmanFord<Int> belman2(N, INF);
  vector<int> A(M), B(M), C(M);
  for(int i=0;i<M;i++){
    cin>>A[i]>>B[i]>>C[i]; A[i]--,B[i]--;
    belman2.add_edge(B[i], A[i], 1);
  }

  for(int i=0;i<M;i++) belman.add_edge(A[i], B[i], P - C[i]);
  auto D2 = belman2.calcD(N-1);
  auto D = belman.calcD(0, D2.first);
  int inf = D.first.empty();
  //pr(D.second);
  //  pr(D2.first);
  for(int i=0;i<N && inf == 0;i++){
    if(D.second[i] > N && D2.first[i] != INF)  inf = 1;
  }

  if(inf)cout<<-1<<endl;
  else cout<<max(0LL, -D.first[N-1])<<endl;


  return 0;
}


Measured memory_bytes: 640