#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#define fast
#else
#define fast cin.tie(0)->sync_with_stdio(0)
#define cerr if(1);else cerr
#define endl '\n'
#endif
#define _ <<' '<<
#define ALL(v) v.begin(),v.end()
#define ft first
#define sd second

using ll = long long;
using ld = long double;
using pii = pair<int,int>;

struct Edge {
	int u, v, w, dist;
	bool visit = false;
	set<int> forbid{};
};

constexpr int INF = 1e9;

signed main() {
	fast;
	
	int m, n, k;
	cin >> m >> n >> k;
	int s, t;
	cin >> s >> t;
	vector<Edge> edge(m);
	map<pii, int> mp{};
	vector<vector<pii>> G(n);
	for (int i = 0; i < m; i++) {
		int u, v, w;
		cin >> u >> v >> w;
		edge[i].u = u;
		edge[i].v = v;
		edge[i].w = w;
		G[u].emplace_back(v, i);
		mp[{ u, v }] = i;
	}
	for (int i = 0; i < k; i++) {
		int x, y, z;
		cin >> x >> y >> z;
		auto it = mp.find({ x, y });
		if (it == mp.end()) continue;
		if (mp.find({ y, z }) == mp.end()) continue;
		edge[it->second].forbid.emplace(z);
	}
	
	int ans = -1;

	priority_queue<tuple<int,int>> pq{};
	auto add = [&](int i, int d) {
		edge[i].dist = d += edge[i].w;
		edge[i].visit = true;
		pq.emplace( -d, i );
	};
	for (auto [y,i]: G[s])
		add(i, 0);
	
	while (!pq.empty()) {
		auto [d,i] = pq.top(); pq.pop();
		d *= -1;
		const auto& e = edge[i];
		if (e.v == t) {
			ans = e.dist;
			break;
		}
		cerr _ i _ d _ e.u _ e.v _ e.w _ endl;
		for (auto [y,j]: G[e.v]) if (!edge[j].visit) {
			if (!e.forbid.count(y)) {
				add(j, d);
			}
		}
	}
	
	if (s == t)
		ans = 0;
	
	cout << ans << endl;
	
	return 0;
}