#include <bits/stdc++.h>
using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<double, double> pdd;
//typedef vector<vector<ll>> Graph;

const ll mod = 1e9 + 7;
//const ll mod = 998244353;

#define REP(i,n) for(ll i=0;i<(ll)n;i++)
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define spa << " " <<
#define fi first
#define se second

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 (a>b) { a=b; return 1; } return 0; }

template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){
os << "(" << v.first << ", " << v.second << ")"; return os;
}
template<class T> ostream& operator << (ostream& os, const vector<T> v){
for(int i = 0; i < (int)v.size(); i++){if(i > 0){os << " ";} os << v[i];} return os;
}
template<class T> ostream& operator << (ostream& os, const vector<vector<T>> v){
for(int i = 0; i < (int)v.size(); i++){if(i > 0){os << endl;} os << v[i];} return os;
}

template<typename T> void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cerr<<v[i][0];for(ll j=1;j<w;j++)cerr spa v[i][j];cerr<<endl;}};
void debug(vector<string>&v,ll h,ll w){for(ll i=0;i<h;i++)
{for(ll j=0;j<w;j++)cerr<<v[i][j];cerr<<endl;}};
template<typename T> void debug(vector<T>&v,ll n){if(n!=0)cerr<<v[0];
for(ll i=1;i<n;i++)cerr spa v[i];
cerr<<endl;};

string num2bit(ll num, ll len){
    string bit = "";
    REP(i, len){
    bit += char('0'+(num>>i & 1));
    }
    return bit;
}

template< typename T >
struct edge {
  int src, to;
  T cost;

  edge(int to, T cost) : src(-1), to(to), cost(cost) {}

  edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}

  edge &operator=(const int &x) {
    to = x;
    return *this;
  }

  operator int() const { return to; }
};

template< typename T >
using Edges = vector< edge< T > >;
template< typename T >
using WeightedGraph = vector< Edges< T > >;
using UnWeightedGraph = vector< vector< int > >;
template< typename T >
using Matrix = vector< vector< T > >;

template< typename T >
vector< T > BellmanFord_without_negative_cycle(WeightedGraph< T > &g, int s) {
  const ll V = g.size();
  const auto INF = numeric_limits< T >::max();
  vector< T > dist(V, INF);
  dist[s] = 0;
  for(int t = 0; t < V - 1; t++) {
    for(int i = 0; i < V; i++){
        for(auto &e: g[i]){
            if(dist[i] == INF) continue;
            dist[e.to] = min(dist[e.to], dist[i] + e.cost);
        }
    }
  }
  // 負閉路チエックはここではしない
  return dist;
}

// s から t への負閉路を含むパスが存在するかどうかを判定する．
// これは，グラフに負閉路が存在するかどうかとは別問題である．
// trueが入っていれば負閉路を含むパスが存在する．
// 引数のdにはBellman-Fordの結果を入れる．
template< typename T >
vector<bool> NegativeCycle_on_path(WeightedGraph< T > &g, vector<T> &d, int s) {
  const ll V = g.size();
  const auto INF = numeric_limits< T >::max();
  auto dist = d;
  for(int t = 0; t < V - 1; t++) {
    for(int i = 0; i < V; i++){
        for(auto &e: g[i]){
            if(dist[i] == INF) continue;

            if(dist[i] == -INF) dist[e.to] = -INF;
            else if(dist[e.to]>dist[i]+e.cost) dist[e.to] = -INF;
        }
    }
  }
  
  vector<bool> negcyc(V, false);
  REP(i, V) if(dist[i] == -INF) negcyc[i] = true;
  return negcyc;
}



// verified @ 
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    ll N, M, P;
    cin >> N >> M >> P;

    WeightedGraph<ll> G(N);
    REP(i, M){
      ll A, B, C;
      cin >> A >> B >> C;
      A--, B--;
      G[A].emplace_back(B, P-C);
    }
    
    auto d = BellmanFord_without_negative_cycle(G, 0);
    //cout << d << endl;
    auto negcyc = NegativeCycle_on_path(G, d, 0);

    cout << (negcyc[N-1] ? -1 : max(-d[N-1], 0ll)) << endl;

    return 0;
}

Measured memory_bytes: 640