#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define X first
#define Y second
#define debug(x) { cout << #x << ' ' << x << '\n'; }
#define pb push_back
#define mp make_pair
#define mt make_tuple
template<typename T> using Min_heap = priority_queue<T, vector<T>, greater<T>>;

int m, n, k;
int v, w;
const int INF = INT_MAX;
vector<vector<pii>> G, rG;
vector<vector<int>> dis;
vector<vector<bool>> vis;
set<tuple<int, int, int>> forbid;

int dijkstra() {
  Min_heap<tuple<int, int, int>> pq; // <W, ind_from, to>
  for (pii i : G[v]) {
    int nfrom = find(rG[i.Y].begin(), rG[i.Y].end(), mp(i.X, v)) - rG[i.Y].begin();
    dis[i.Y][nfrom] = i.X;
    pq.push({dis[i.Y][nfrom], nfrom, i.Y});
  }
  // cerr << (forbid.find(mt(4, 1, 5))!=forbid.end()) << ' ' << (forbid.find(mt(1, 5, 4))!=forbid.end()) << '\n';
  while (!pq.empty()) {
    auto [D, ind_from, now] = pq.top();
    pq.pop();
    // if (D > rG[now][ind_from].X) continue;
    if (vis[now][ind_from]) continue;
    vis[now][ind_from] = 1;
    int from = rG[now][ind_from].Y;
    for (pii i : G[now]) {
      if (forbid.find(mt(from, now, i.Y)) != forbid.end()) continue;
      int nfrom = find(rG[i.Y].begin(), rG[i.Y].end(), mp(i.X, now)) - rG[i.Y].begin();
      if (dis[i.Y][nfrom] > D + i.X) {
        dis[i.Y][nfrom] = D + i.X;
        pq.push({dis[i.Y][nfrom], nfrom, i.Y});
      }
    }
  }
  int ans = INF;
  for (int i = 0; i < (int)rG[w].size(); i++) {
    ans = min(ans, dis[w][i]);
  }
  return ans;
}

signed main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> m >> n >> k;
  cin >> v >> w;
  G.resize(n);
  rG.resize(n);
  dis.resize(n);
  vis.resize(n);
  for (int i = 0; i < m; i++) {
    int x, y, c;
    cin >> x >> y >> c;
    G[x].pb({c, y});
    rG[y].pb({c, x});
    // if (x == v) dis[y].pb(c);
    // else dis[y].pb(INF);
    dis[y].pb(INF);
    vis[y].pb(false);
  }
  for (int i = 0; i < k; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    forbid.insert({x, y, z});
  }
  int ans = dijkstra();
  /*
  for (int i = 0; i < n; i++) {
    cerr << i << ": \n";
    for (int j = 0; j < (int)rG[i].size(); j++) {
      cerr << rG[i][j].Y << "-" << rG[i][j].X << " " << dis[i][j] << '\n';
    }
    cerr << '\n';
  }
  */
  if (ans == INF) cout << "-1\n";
  else cout << ans << '\n';
  return 0;
}