#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using vi = vector<int>;
using vll = vector<ll>;
using vvi = vector<vector<int>>;
using vvl = vector<vector<ll>>;

ll INF = 1010101010101010LL;
vector<vector<pair<int, ll>>> ps;

struct N {
  ll i, d;

  N(int i, ll d) : i(i), d(d) {}
};

bool operator<(const N &l, const N &r) {
  return l.d > r.d;
}

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  ll n, m, p, q, t;
  cin >> n >> m >> p >> q >> t;
  p--;
  q--;

  vector<ll> fromp(n, INF), fromq(n, INF), from1(n, INF);
  ps.resize(n);

  for (int i = 0; i < m; i++) {
    ll a, b, c;
    cin >> a >> b >> c;
    a--;
    b--;
    ps[a].emplace_back(b, c);
    ps[b].emplace_back(a, c);
  }

  priority_queue<N> queue;
  queue.emplace(p, 0);
  while (queue.size()) {
    auto v = queue.top();
    queue.pop();
    if (fromp[v.i] < INF) continue;
    fromp[v.i] = v.d;
    for (auto &path : ps[v.i]) {
      if (fromp[path.first] < INF) continue;
      queue.emplace(path.first, v.d + path.second);
    }
  }

  queue.emplace(q, 0);
  while (queue.size()) {
    auto v = queue.top();
    queue.pop();
    if (fromq[v.i] < INF) continue;
    fromq[v.i] = v.d;
    for (auto &path : ps[v.i]) {
      if (fromq[path.first] < INF) continue;
      queue.emplace(path.first, v.d + path.second);
    }
  }

  queue.emplace(0, 0);
  while (queue.size()) {
    auto v = queue.top();
    queue.pop();
    if (from1[v.i] < INF) continue;
    from1[v.i] = v.d;
    for (auto &path : ps[v.i]) {
      if (from1[path.first] < INF) continue;
      queue.emplace(path.first, v.d + path.second);
    }
  }

  ll ans = -1;
  for (int i = 0; i < n; i++) {
    ll pcost = fromp[i] * 2;
    ll qcost = fromq[i] * 2;
    ll cost = from1[i] * 2;
    if (max(pcost, qcost) + cost <= t) {
      ans = max(ans, t - max(pcost, qcost));
    }
  }
  if (from1[p] + from1[q] + fromp[q] <= t) {
    ans = t;
  }

  cout << ans << endl;

  return 0;
}