#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < int(n); i++)
#define rep1(i,n) for (int i = 1; i <= int(n); i++)
#define repR(i,n) for (int i = int(n)-1; i >= 0; i--)
#define rep1R(i,n) for (int i = int(n); i >= 1; i--)
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define fst first
#define snd second
#define cauto const auto
#ifdef LOCAL
#define dump(...) cerr << "[" << __LINE__ << ":" << __FUNCTION__ << "] ", _dmp_(#__VA_ARGS__, __VA_ARGS__);
void _dmp_(const char*) { cerr << endl; }
template <class T, class... U>
void _dmp_(const char *s, T const& x, U const& ...y) { const char *o = "({[", *e = "]})"; for (int i = 0; *s != '\0'; cerr << *s++) { if (count(o,o+3,*s)) i++; if (count(e,e+3,*s)) i--; if (!i && *s == ',') break; } cerr << " = " << x; if (*s == ',') cerr << ", ", s++; _dmp_(s, y...); }
#else
#define dump(...)
#endif
using ll = long long;
#define int ll
template <class T> using pque_max = priority_queue<T>;
template <class T> using pque_min = priority_queue<T, vector<T>, greater<T> >;
#define CONAINER_OUTPUT os << "{"; for (auto const& x : v) os << " " << x; return os << " }";
template <class T> ostream& operator<<(ostream& os, vector<T> const& v) { CONAINER_OUTPUT }
template <class T> ostream& operator<<(ostream& os, deque<T> const& v) { CONAINER_OUTPUT }
template <class T> ostream& operator<<(ostream& os, set<T> const& v) { CONAINER_OUTPUT }
template <class T, class U> ostream& operator<<(ostream& os, map<T,U> const& v) { CONAINER_OUTPUT }
#undef CONAINER_OUTPUT
template <class T> istream& operator>>(istream& is, vector<T>& v) { for (auto& x : v) is >> x; return is; }
template <class T, class S> ostream& operator<<(ostream& os, pair<T,S> const& p) { return os << "(" << p.first << ", " << p.second << ")"; }
template <class T, class S> istream& operator>>(istream& is, pair<T,S> const& p) { return is >> p.first >> p.second; }
struct _Init_ { _Init_() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); } } _init_;

template <class T> void quit(T const& x) { cout << x << endl; exit(0); }
template <class T> bool chmin(T& x, T const& y) { if (x > y) { x = y; return true; } return false; }
template <class T> bool chmax(T& x, T const& y) { if (x < y) { x = y; return true; } return false; }
template <class It> auto sumof(It b, It e) { return accumulate(b,e,typename iterator_traits<It>::value_type{}); }
#define YesNo(c) ((c) ? "Yes" : "No")
////////////////////////////////
int n,m,p;
struct edge { int cost,to; };
vector<vector<edge> > g,rg;
vector<int> d,used;
const int inf = 1e15;

void dfs(int s) {
    used[s] |= 1;
    for (edge e : g[s]) if (!(used[e.to]&1)) dfs(e.to);
}

void rdfs(int s) {
    used[s] |= 2;
    for (edge e : rg[s]) if (!(used[e.to]&2)) rdfs(e.to);
}

int32_t main() {
    cin >> n >> m >> p;
    g.resize(n); rg.resize(n); used.resize(n);
    d.assign(n,-inf);
    rep (i,m) {
        int a,b,c; cin >> a >> b >> c; a--,b--;
        g[a].push_back({c-p,b});
        rg[b].push_back({c-p,a});
    }
    const int s = 0, t = n-1;
    dfs(s); rdfs(t);
    d[s] = 0;
    rep (_,n-1) {
        rep (x,n) for (edge e : g[x]) chmax(d[e.to], d[x] + e.cost);
    }
    int temp = d[t];
    rep (_,n) {
        rep (x,n) for (edge e : g[x]) {
            if (chmax(d[e.to], d[x] + e.cost) && used[e.to] == 3) quit(-1);
        }
    }
    cout << max(temp,0LL) << endl;
    
}


Measured memory_bytes: 768