#include <iostream>
#include <vector>
#include <map>
#include <queue>
#define int long long
using namespace std;
const int inf = 1e18;

int cost[300005];
int dis[300005];

vector<int> in[30005], out[30005];
vector<pair<int, int> > adj[300005];

signed main()
{
    ios::sync_with_stdio(false); cin.tie(0);
    int m, n, k; cin >> m >> n >> k;
    int a, b; cin >> a >> b;
    map<pair<int, int>, int> re;
    for (int i = 0; i < m; i++) {
        int u, v; cin >> u >> v >> cost[i];
        in[v].push_back(i);
        out[u].push_back(i);
        re[make_pair(u, v)] = i;
    }
    map<pair<int, int>, int> mp;
    for (int i = 0; i < k; i++) {
        int u, v, w; cin >> u >> v >> w;
        mp[make_pair(re[make_pair(u, v)], re[make_pair(v, w)])] = 1; 
    }
    for (int i = 0; i < n; i++) {
        for (int j: in[i]) {
            for (int k: out[i]) {
                if (!mp[make_pair(j, k)]) adj[j].push_back(make_pair(cost[k], k));
            }
        }
    }
    fill(dis, dis + 300005, inf);
    priority_queue<pair<int, int> > pq;
    for (int i: out[a]) {
        dis[i] = cost[i];
        pq.push(make_pair(-dis[i], i));
    }
    while (!pq.empty()) {
        int cur = pq.top().second;
        int dst = -pq.top().first;
        pq.pop();
        for (pair<int, int> p: adj[cur]) {
            if (dis[p.second] > dst + p.first) {
                dis[p.second] = dst + p.first;
                pq.push(make_pair(-dis[p.second], p.second));
            }
        }
    }
    int ans = inf;
    for (int i: in[b]) {
        ans = min(ans, dis[i]);
    }
    cout << (ans == inf ? -1 : ans) << '\n';
    return 0;
}