#include <iostream>
#include <iomanip>
#include <string>
#include <stack>
#include <vector>
#include <math.h>
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <iterator>
#include <map>
#include <set>
#include <queue>
#include <list>
#include <regex>
using namespace std;
using pii  = pair<int,int>;
using ll=long long;
using ld=long double;
#define pb push_back
#define mp make_pair
#define sc second
#define fr first
#define stpr setprecision
#define cYES cout<<"YES"<<endl
#define cNO cout<<"NO"<<endl
#define cYes cout<<"Yes"<<endl
#define cNo cout<<"No"<<endl
#define rep(i,n) for(ll i=0;i<(n);++i)
#define Rep(i,a,b) for(ll i=(a);i<(b);++i)
#define rrep(i,n) for(int i=n-1;i>=0;i--)
#define rRep(i,a,b) for(int i=a;i>=b;i--)
#define crep(i) for(char i='a';i<='z';++i)
#define psortsecond(A,N) sort(A,A+N,[](const pii &a, const pii &b){return a.second<b.second;});
#define ALL(x) (x).begin(),(x).end()
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define endl '\n'
int ctoi(const char c){
  if('0' <= c && c <= '9') return (c-'0');
  return -1;
}
ll gcd(ll a,ll b){return (b == 0 ? a : gcd(b, a%b));}
ll lcm(ll a,ll b){return a*b/gcd(a,b);}
constexpr ll MOD=1000000007;
constexpr ll INF=1000000011;
constexpr ll MOD2=998244353;
constexpr ll LINF = 1001002003004005006ll;
constexpr ld EPS=10e-8;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<typename T> istream& operator>>(istream& is,vector<T>& v){for(auto&& x:v)is >> x;return is;}
template<typename T,typename U> istream& operator>>(istream& is, pair<T,U>& p){ is >> p.first; is >> p.second; return is;}
template<typename T,typename U> ostream& operator>>(ostream& os, const pair<T,U>& p){ os << p.first << ' ' << p.second; return os;}
template<class T> ostream& operator<<(ostream& os, vector<T>& v){
  for(auto i=begin(v); i != end(v); ++i){
    if(i !=begin(v)) os << ' ';
    os << *i;
  }
  return os;
}

ll C[100007];
 
// 隣接リストで使う辺を表す型
struct Edge {
  ll to, cost;  // 辺の接続先頂点, 辺の重み
  Edge(ll to, ll cost) : to(to), cost(cost) {}  // コンストラクタ
};

typedef vector<vector<Edge> > AdjList;
AdjList graph;  // グラフの辺を格納した構造体
                // graph[v][i]は頂点vから出るi番目の辺Edge

vector<ll> DIS; // 最短距離

// 戻り値がtrueなら負の閉路を含む
bool bellman_ford(ll N, ll s) { // nは頂点数、sは開始頂点
  DIS = vector<ll>(N+1, LINF);
  DIS[s] = 0; // 開始点の距離は0
  rep(i,N+1){
    Rep(v,1,N+1){   
      if(C[v]!=2){
        continue;
      }   //ここ
      rep(k,graph[v].size()){
        Edge e = graph[v][k];
        if(C[e.to]!=2){
          continue;
        }
        if(DIS[v] != LINF && DIS[e.to] > DIS[v] + e.cost) {
          DIS[e.to] = DIS[v] + e.cost;
          if(i==N){
            return true; // n回目にも更新があるなら負の閉路が存在
          }
        }
      }
    }
  }
  return false;
}

int main() {
  ll N, M, P;
  cin >> N >> M >> P;

  graph = AdjList(N+1);
  vector<vector<ll>> bfsgraph1(N+1),bfsgraph2(N+1);

  rep(i,M){
    ll X, Y, L;
    cin >> X >> Y >> L;
    L=-(L-P);
    graph[X].push_back(Edge(Y, L));
    bfsgraph1[Y].pb(X);
    bfsgraph2[X].pb(Y);
  }

  queue<ll> Q;

  Q.push(N);
  C[N]=1;
  while(!Q.empty()){
    auto X = Q.front();
    Q.pop();
    rep(i,bfsgraph1[X].size()){
      if(C[bfsgraph1[X][i]]==0){
        Q.push(bfsgraph1[X][i]);
        C[bfsgraph1[X][i]]=1;
      }
    }
  }

  Q.push(1);
  C[1]=2;
  while(!Q.empty()){
    auto X = Q.front();
    Q.pop();
    rep(i,bfsgraph2[X].size()){
      if(C[bfsgraph2[X][i]]==1){
        Q.push(bfsgraph2[X][i]);
        C[bfsgraph2[X][i]]=2;
      }
    }
  }

  bool F = bellman_ford(N, 1);

  if(F){
    cout << -1 << endl;
    return 0;
  }
  cout <<  max(0LL,-DIS[N]) << endl;
}

Measured memory_bytes: 768