#include <iostream>
#include <array>
#include <vector>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <algorithm>
#include <math.h>
#include <string>
#include <climits>
#include <assert.h>
#include <iomanip>
#include <bitset>
#include <queue>
#include <deque>
#include <stack>
#include <functional>
#include <fstream>

#define FOR(i,a,n) for(int i=(a);i<(n); ++i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define IS_BIT_ON(bit, i) (bit & (1 << i))
#define BIT_ON(bit, i) (bit |= (1 << i))
#define BIT_OFF(bit, i) (bit &= ~(1 << i))
#define BIT_COUNT(bit) (__builtin_popcount(bit))

typedef long long LL;
template<typename T> std::vector<T> make_v(size_t a){return std::vector<T>(a);}
template<typename T,typename... Ts> auto make_v(size_t a, Ts... ts){ return std::vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));}    // C++14
template<typename T,typename V> typename std::enable_if<std::is_class<T>::value==0>::type fill_v(T &t,const V &v){t=v;}
template<typename T,typename V> typename std::enable_if<std::is_class<T>::value!=0>::type fill_v(T &t,const V &v){for(auto &e:t) fill_v(e,v);}
template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
void print() { std::cout << std::endl; }
template <class Head, class... Tail> void print(Head&& head, Tail&&... tail) { std::cout << head; if (sizeof...(tail) != 0) {std::cout << " ";} print(std::forward<Tail>(tail)...); }
template <class T> void print(std::vector<T> &v) {for (auto& a : v) { std::cout << a; if (&a != &v.back()) {std::cout << " ";} }std::cout << std::endl;}
template <class T> void print(std::vector<std::vector<T>> &vv) { for (auto& v : vv) { print(v); }}
void debug() { std::cerr << std::endl; }
template <class Head, class... Tail> void debug(Head&& head, Tail&&... tail) { std::cerr << head; if (sizeof...(tail) != 0) {std::cerr << " ";} print(std::forward<Tail>(tail)...); }
template <class T> void debug(std::vector<T> &v) {for (auto& a : v) { std::cerr << a; if (&a != &v.back()) {std::cerr << " ";} }std::cerr << std::endl;}
template <class T> void debug(std::vector<std::vector<T>> &vv) { for (auto& v : vv) { print(v); }}
inline bool inside(long long y, long long x, long long H, long long W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }
template<typename T> T &chmin(T &a, const T &b) { return a = std::min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = std::max(a, b); }

template<class T> inline std::vector<T> unique(std::vector<T> v) {
    sort(v.begin(), v.end());
    v.erase(unique(v.begin(), v.end()), v.end());
    return v;
}

long long sum_of_arithmetic_progression(long long s, long long d, long long n) {
    return n * (2 * s + (n - 1) * d) / 2;
}

bool is_power_of_two(long long x) {
    return !(x & (x - 1));
}

long long gcd(long long a, long long b) {
    if (b == 0) { return a; }
    return gcd(b, a % b);
}

long long gcd(std::vector<long long> &v) {
    long long ans = v[0];
    for (int i = 1; i < (int)v.size(); ++i) {
        ans = gcd(ans, v[i]);
    }
    return ans;
}

long long lcm(long long a, long long b) {
    long long g = gcd(a, b);
    return a / g * b;
}

const int INF = 1u << 30u;
const long long LINF = 1ull << 58u;
const double EPS = 1e-9;
const long double PI = acos(-1.0);
const std::vector<int> dy2 = {0, 1}, dx2 = {1, 0};
const std::vector<int> dy4 = {0, 1, 0, -1}, dx4 = {1, 0, -1, 0};
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;

class Edge {
public:
    const int no = 0;
    const int from = 0;
    const int to = 0;
    const long long weight = 0;

    Edge() {}

    Edge(int no, int from, int to, long long weight) : no(no), from(from), to(to), weight(weight) {
    }

    bool operator<(const Edge& edge) const {
        return this->weight < edge.weight;
    }
    bool operator>(const Edge& edge) const {
        return this->weight > edge.weight;
    }

};

class Graph {
public:
    const int N;    // ノード数
    int M = 0;      // エッジ数
    std::vector<std::vector<Edge>> graph;
    Graph(int N) : N(N) {
        this->graph.resize(N);
    }

    void add_undirected_edge(const int no, const int u, const int v, const long long w) {
        this->graph.at(u).emplace_back(Edge(no, u, v, w));
        this->graph.at(v).emplace_back(Edge(no, v, u, w));
        this->M++;
    }

    void add_directed_edge(const int no, const int from, const int to, const long long w) {
        this->graph.at(from).emplace_back(Edge(no, from, to, w));
        this->M++;
    }

    std::vector<Edge> &operator[](const int u) {
        return this->graph[u];
    }

    std::vector<std::vector<long long>> make_matrix_graph() {
        std::vector<std::vector<long long>> matrix(this->N, std::vector<long long>(this->N, INT_MAX));
        for (const auto &v : this->graph) {
            for (const auto &e : v) {
                matrix[e.from][e.to] = e.weight;
            }
        }
        return matrix;
    }

    // mode 0: undirected edge
    // mode 1: directed edge
    void show(int mode = 0) {
        std::cout << this->M << std::endl;
        for (const auto &v : this->graph) {
            for (const auto &e : v) {
                if (mode == 0) {
                    if (e.from < e.to) {
                        std::cout << e.from << " " << e.to << std::endl;
                    }
                }
                else {
                    std::cout << e.from << " " << e.to << std::endl;
                }
            }
        }
    }
};

std::vector<long long> bellman_ford(const int start, const int num_node, const std::vector<Edge> &edges) {
    std::vector<long long> distance(num_node, LONG_LONG_MAX);
    distance[start] = 0;
    std::vector<unsigned int> prev(num_node, -1);

    int i;
    for (i = 0; i < num_node; ++i) {
        bool update = false;
        for (const auto &e : edges) {
            unsigned int from = e.from, to = e.to;
            long long cost = e.weight;
            if (distance.at(from) != LONG_LONG_MAX and distance.at(to) > distance.at(from) + cost) {
                distance.at(to) = distance.at(from) + cost;
                prev.at(to) = from;
                update = true;
            }
        }
        if (not update) { break; }
    }

    if (i == num_node) {
        return {};
    }
    else {
        return distance;
    }
}


void dfs(int u, Graph &g, vector<bool> &can_reach) {
    can_reach[u] = true;

    FOE(e, g[u]) {
        if (not can_reach[e.to]) {
            dfs(e.to, g, can_reach);
        }
    }
}

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

    LL N, M, P;
    cin >> N >> M >> P;

    auto A = make_v<LL>(M);
    auto B = make_v<LL>(M);
    auto C = make_v<LL>(M);
    Graph g1(N);
    FOR(i, 0, M) {
        LL a, b, c;
        cin >> a >> b >> c;
        a--; b--;
        A[i] = a;
        B[i] = b;
        C[i] = c;
        g1.add_directed_edge(i, b, a, 0);
    }

    auto can_reach = make_v<bool>(N);
    dfs(N - 1, g1, can_reach);

    auto edges = make_v<Edge>(0);
    FOR(i, 0, M) {
        LL a = A[i], b = B[i], c = C[i];

        if (can_reach[a] and can_reach[b]) {
            edges.emplace_back(Edge(i, a, b, -(c - P)));
        }
    }

    auto cost = bellman_ford(0, N, edges);
    if (cost.empty()) {
        print(-1);
        return 0;
    }
    print(max(0ll, -cost[N - 1]));

    return 0;
}


Measured memory_bytes: 1024