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

#define fs first
#define sc 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 (b<a) { a=b; return 1; } return 0; }


// std::vector Declaration
template<typename T>
vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}

// std::vector Initialization
template<typename T>
void fill_all(T& arr, const T& v) { arr = v; }
template<typename T, typename U>
void fill_all(T& arr, const U& v) { for (auto& i : arr) fill_all(i, v); }

// std::vector Debug
template<typename T>
ostream& operator<<(ostream& os, const vector<T>& v) {
    os << "[";
    bool a = 1;
    for (auto e : v) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::deque Debug
template<typename T>
ostream& operator<<(ostream& os, const deque<T>& d) {
    os << "[";
    bool a = 1;
    for (auto e : d) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "]";
    return os;
}

// std::pair Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const pair<T, U>& p) {
    os << "(" << p.first << " " << p.second << ")";
    return os;
}

// std::set Debug
template<typename T>
ostream& operator<<(ostream& os, const set<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::multiset Debug
template<typename T>
ostream& operator<<(ostream& os, const multiset<T>& st) {
    os << "{";
    bool a = 1;
    for (auto e : st) {
        os << (a ? "" : " ");
        os << e;
        a = 0;
    }
    os << "}";
    return os;
}

// std::map Debug
template<typename T, typename U>
ostream& operator<<(ostream& os, const map<T, U>& mp) {
    os << "{";
    bool a = 1;
    for (auto e : mp) {
        os << (a ? "" : " ");
        os << e.first << ":" << e.second;
        a = 0;
    }
    os << "}";
    return os;
}

// std::tuple Debug
template<int N, class Tuple>
void out(ostream& os, const Tuple& t){}
template<int N, class Tuple, class H, class ...Ts>
void out(ostream& os, const Tuple& t) {
    if (N) os << " ";
    os << get<N>(t);
    out<N+1,Tuple,Ts...>(os, t);
}
template<class ...Ts>
ostream& operator<<(ostream& os, const tuple<Ts...>& t) {
    os << "(";
    out<0,tuple<Ts...>,Ts...>(os, t);
    os << ")";
    return os;
}

// Debug
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl



const LL LINF = 1LL<<60;
const int IINF = 1<<30;
const LL MOD = 1e9+7;

struct edge { int from, to, cost; };
ostream& operator<<(ostream& os, const edge& e) {
    os << "(" << e.to << ", " << e.cost << ")";
    return os;
}

void bellman_ford(const vector<edge>& E, vector<LL>& d, vector<bool>& neg, int s) {
    fill(d.begin(), d.end(), LINF);
    fill(neg.begin(), neg.end(), false);
    d[s] = 0;
    bool updated = true;
    for (int i = 0; i < 2*d.size()-1 && updated; ++i) {
        updated = false;
        for (int j = 0; j < E.size(); ++j) {
            int u = E[j].from, v = E[j].to, cost = E[j].cost;
            if (d[u] == LINF) continue;
            if (d[v] > d[u] + cost) {
                d[v] = d[u] + cost;
                updated = true;
                if (i >= d.size() - 1) neg[v] = true;
            }
        }
    }
}

int main()
{
    int n, m, p; cin >> n >> m >> p;
    vector<edge> E(m);
    for (int i = 0; i < m; ++i) {
        int a, b, c; cin >> a >> b >> c;
        --a; --b;
        E[i] = (edge){ a, b, -(c-p) };
    }

    vector<LL> d(n);
    vector<bool> neg(n);

    bellman_ford(E, d, neg, 0);

    if (neg[n-1]) {
        cout << -1 << endl;
    } else {
        cout << max(-d[n-1], 0LL) << endl;
    }

    return 0;
}


Measured memory_bytes: 384