#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define PB push_back
#define FS first
#define SD second
#define ary(k) array<int,k>
template<class A,class B> void cmx(A& x, B y) {x=max<A>(x,y);}
template<class A,class B> void cmn(A& x, B y) {x=min<A>(x,y);}
typedef pair<int, int> pii;
typedef vector<int> vi;

int dist[100002][11];
vector<pii> kra[100002];

signed main() {
    cin.tie(0)->sync_with_stdio(0); cin.exceptions(cin.failbit);
    int n, m, q;
    cin >> m >> n >> q;
    int s, t;
    cin >> s >> t;
    for (int i = 0; i <= n; i++) {
        for (int j = 0; j < 10; j++) {
            dist[i][j] = 1000000000000000001ll;
        }
    }
    for (int i = 0; i < m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        kra[u].PB({v, w});
    }
    set<array<int, 3>> forbidden;
    for (int i = 0; i < q; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        forbidden.insert({a, b, c});
    }
    kra[n].PB({s, 0});
    dist[n][0] = 0;
    priority_queue<array<int, 3>, vector<array<int, 3>>, greater<array<int, 3>>> pq;
    pq.push({0, n, 0});
    int best = 1000000000000000001ll;
    while (!pq.empty()) {
        auto [d, v, nv] = pq.top();
        pq.pop();
        if (d > dist[v][nv])
            continue;
        int u = kra[v][nv].FS;
        for (int i = 0; i < sz(kra[u]); i++) {
            auto [nu, nw] = kra[u][i];
            if (forbidden.find({v, u, nu}) != forbidden.end())
                continue;
            int nd = d + nw;
            if (nd < dist[u][i]) {
                dist[u][i] = nd;
                pq.push({nd, u, i});
                if (nu == t)
                    cmn(best, nd);
            }
        }
    }
    if (best == 1000000000000000001ll)
        best = -1;
    cout << best << "\n";
}