#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;

#ifdef WAIMAI
#define debug(HEHE...) cout<<"["<<#HEHE<<"] : ",dout(HEHE)
void dout(){cout<<'\n';}
template<typename T,typename...U>
void dout(T t,U...u){cout<<t<<(sizeof...(u)?", ":""),dout(u...);}
#else
#define debug(...) 7122
#endif

#define int long long
#define ll long long
#define Waimai ios::sync_with_stdio(false),cin.tie(0)
#define FOR(x,a,b) for(int x=a,I=b;x<=I;x++)
#define pb emplace_back
#define F first
#define S second

const int INF = 2e9;
const int SIZE = 1e5 + 5;

int n, m, ans;
int u, d;
int dis[SIZE];
vector<pair<int, int>> adj[SIZE];
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;

void solve() {
    cin >> n >> m >> u >> d;
    while (m--) {
        int a, b, w;
        cin >> a >> b >> w;
        a++, b++;
        adj[a].pb (b, w);
        adj[b].pb (a, w);
    }

    fill (dis, dis + n + 1, INF);
    dis[1] = 0, pq.emplace (0, 1);
    while (pq.size()) {
        auto [val, pos] = pq.top();
        pq.pop();
        if (val > dis[pos]) continue;
        for (auto [np, w] : adj[pos]) if (val + w < dis[np]) {
            dis[np] = val + w;
            pq.emplace (dis[np], np);
        }
    }

    FOR (i, 1, n) for (auto [j, w] : adj[i]) {
        int val = min (dis[i], dis[j]);
        if (2 * val < d) ans++;
    }
    cout << ans / 2 << '\n';
}

int32_t main() {
    Waimai;
	solve();
}