#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T> using treap = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
using Int = long long;
#define REP(i, n) for (long long i = 0, max_i = (n); i < max_i; i++)
#define REPI(i, a, b) for (long long i = (a), max_i = (b); i < max_i; i++)
#define ALL(obj) begin(obj), end(obj)
#define RALL(obj) rbegin(obj), rend(obj)
#define fi first
#define se second
using ii = pair<Int, Int>;
vector<ii> dirs = {
    {1, 0}, {0, 1}, {-1, 0}, {0, -1},  // 4方向
    {1, 1}, {-1, 1}, {-1, -1}, {1, -1},  // 斜め
    {0, 0},  // 自身
};
Int get_msb(long long x) {
    assert(x != 0);
    return 63 - __builtin_clzll(x);
}
Int get_lsb(long long x) {
    assert(x != 0);
    return __builtin_ctzll(x);
}
template <class T> inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }
template <class T> inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template <class T, class S> vector<T> make_vec(size_t n, S x) { return vector<T>(n, x); }
template <class T, class... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec<T>(ts...))>(n, make_vec<T>(ts...)); }

// debug
template <class T> ostream& operator<<(ostream& s, const vector<T>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : " "); return s; }
template <class T> ostream& operator<<(ostream& s, const vector<vector<T>>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : "\n"); return s; }
template <class T, class S> ostream& operator<<(ostream& s, const pair<T, S>& p) { s << "{" << p.first << ", " << p.second << "}"; return s; }
template <class T> ostream& operator<<(ostream& s, const set<T> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T> ostream& operator<<(ostream& s, const multiset<T> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T, class S> ostream& operator<<(ostream& s, const map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T, class S> ostream& operator<<(ostream& s, const unordered_map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
#ifdef _MY_DEBUG
    #define dump(...) cerr << "/* " << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]" << endl, dump_func(__VA_ARGS__), cerr << "*/\n\n";
#else
    #define dump(...)
    #define endl "\n"
#endif
void dump_func() { cerr << endl; }
template <class Head, class... Tail> void dump_func(Head&& h, Tail&&... t) { cerr << h << (sizeof...(Tail) == 0 ? "" : ", "), dump_func(forward<Tail>(t)...); }

struct FastIO { FastIO() { cin.tie(nullptr); ios::sync_with_stdio(false); } } fast_io;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
constexpr Int MOD = 1000000007;
// **********************************************************************************************
// **********************************************************************************************
// **********************************************************************************************
// **************************************** TEMPLATE END ****************************************
// **********************************************************************************************
// **********************************************************************************************
// **********************************************************************************************

template <class T>
struct Edge {
    int from, to;
    T cost;
};
template <class T>
vector<T> bellman_ford(vector<Edge<T>>& edges, int n, int s) {
    constexpr T INF = 1e18;
    vector<T> dist(n, INF);
    dist[s] = 0;
    for (int i = 0; i < n - 1; i++) {
        for (Edge<T>& e : edges) {
            dist[e.to] = min(dist[e.to], dist[e.from] + e.cost);
        }
    }
    // コスト負のループ検出
    for (Edge<T>& e : edges) {
        if (dist[e.from] + e.cost < dist[e.to]) return vector<T>();
    }
    return dist;
}

void dfs(vector<vector<ii>>& g, vector<bool>& visited, Int v) {
    if (visited[v]) return;
    visited[v] = true;
    for (ii p : g[v]) {
        dfs(g, visited, p.fi);
    }
}
signed main() {
    Int n, m, P; cin >> n >> m >> P;
    vector<vector<ii>> str(n), rev(n);
    REP (i, m) {
        Int a, b, c; cin >> a >> b >> c;
        a--, b--;
        str[a].push_back({b, c});
        rev[b].push_back({a, c});
    }
    vector<bool> visited_str(n), visited_rev(n);
    dfs(str, visited_str, 0);
    dfs(rev, visited_rev, n - 1);
    vector<bool> visited(n);
    REP (i, n) visited[i] = visited_str[i] && visited_rev[i];
    vector<Edge<Int>> edges;
    REP (i, n) {
        for (ii p : str[i]) {
            if (visited[i] && visited[p.fi]) {
                edges.push_back({i, p.fi, P - p.se});
            }
        }
    }
    auto dist = bellman_ford(edges, n, 0);
    cout << (dist.empty() ? -1 : max(0LL, -dist[n - 1])) << endl;
}


Measured memory_bytes: 1024