// villanyauto.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <queue>

#define ll long long
using namespace std;
struct ut
{
    ll hova, hossz;

};
priority_queue<ut>que;
ut akt;
bool operator<(const ut& a, const ut& b)
{
    return a.hossz > b.hossz;
}
struct adat
{
    bool lat = false;
    ll hossz = LLONG_MAX;
    vector < pair<ll, ll>>sz;
};

vector<adat>x;
ll n, m, k, a, b, c;
int main()
{
    cin >> n >> m >> k;
    x.resize(n + 1);

    for (int i = 1; i <= m; ++i)
    {
        cin >> a >> b >> c;
        x[a].sz.push_back({ b,c });

    }
    ll ans = 0;
    que.push({ 1,0 });
    while (!que.empty())
    {
        bool ok = false;
        akt = que.top();
        while (x[akt.hova].lat && !que.empty())
        {
            que.pop();
            if (!que.empty())akt = que.top();
        }
        if (que.empty())break;
        que.pop();
        x[akt.hova].lat = true;
        x[akt.hova].hossz = akt.hossz;
        for (auto& e : x[akt.hova].sz)
        {
            if (!x[e.first].lat && x[e.first].hossz > (akt.hossz + e.second))
            {
                ok = true;
                x[e.first].hossz = akt.hossz + e.second;
                que.push({ e.first , akt.hossz + e.second });
            }
            if (!ok)ans += x[akt.hova].hossz;
        }
    }
    
    cout << ans / k;

    return 0;
}

// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

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