#include <bits/stdc++.h>
#define int long long
#define MULTITEST false
using namespace std;
const int INF = 5e17;
struct Road {
int a, b, cost;
int next (int u) {
return u == a ? b : a;
}
};
vector<Road> road_list;
vector<vector<int>> roads;
int N;
vector<int> dijkstra (int start) {
priority_queue<pair<int, int>> queue;
vector<int> distances(N, INF);
distances[start] = 0;
queue.push({ 0, start });
while (queue.size() != 0) {
pair<int, int> u = queue.top();
queue.pop();
int curr = u.second;
int dist = - u.first;
if (distances[curr] != dist) continue ;
for (int r_id : roads[curr]) {
int next = road_list[r_id].next(curr);
int cost = dist + road_list[r_id].cost;
if (distances[next] <= cost) continue ;
distances[next] = cost;
queue.push({ - cost, next });
}
}
return distances;
}
void solve () {
cin >> N;
int M; cin >> M;
int s, t, l, k;
cin >> s >> t >> l >> k;
s --; t --;
roads.resize(N);
for (int i = 0; i < M; i ++) {
int a, b, c;
cin >> a >> b >> c;
a --,
b --;
road_list.push_back({ a, b, c });
roads[a].push_back(i);
roads[b].push_back(i);
}
int count = 0;
vector<int> d_s = dijkstra(s);
vector<int> d_t = dijkstra(t);
if (d_s[t] <= k) {
count = (N * (N - 1)) >> 1;
cout << count << "\n";
return ;
}
for (int a = 0; a < N; a ++) {
for (int b = a + 1; b < N; b ++) {
int dAB = d_s[a] + l + d_t[b];
int dBA = d_s[b] + l + d_t[a];
if (min(dAB, dBA) <= k)
count ++;
}
}
cout << count << "\n";
}
signed main () {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int T = 1;
if (MULTITEST) cin >> T;
for (int t = 0; t < T; t ++) solve();
}
