#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
const int mxN = 2e5 + 100;
const int INF = 1e9;
int par[mxN], sz[mxN], dist[mxN];
vector<pair<int, int>> adj[mxN];
struct dsu{
void init(int n){
for(int i = 1; i <= n; ++i){
par[i] = i, sz[i] = 1;
}
}
int find_par(int u){
if(par[u] == u) return u;
return par[u] = find_par(par[u]);
}
void unite(int u, int v){
u = find_par(u), v = find_par(v);
if(u == v) return;
if(sz[u] > sz[v]){
sz[u] += sz[v];
par[v] = u;
}else{
sz[v] += sz[u];
par[u] = v;
}
}
bool connected(int u, int v){
return find_par(u) == find_par(v);
}
}ds;
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
int n, m, q, u, v, w, k;
cin >> n >> m;
vector<pair<int, int>> edge;
for(int i = 1; i <= n; ++i) dist[i] = INF;
for(int i = 1; i <= m; ++i){
cin >> u >> v >> w;
adj[u].push_back({v, w});
adj[v].push_back({u, w});
edge.push_back({u, v});
}
cin >> k;
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
for(int i = 1; i <= k; ++i){
cin >> u;
dist[u] = 0;
pq.push({0, u});
}
while(pq.size()){
auto tp = pq.top();
pq.pop();
if(tp.first > dist[tp.second]) continue;
for(auto it : adj[tp.second]){
if(dist[it.first] > tp.first + it.second){
dist[it.first] = tp.first + it.second;
pq.push({dist[it.first], it.first});
}
}
}
cin >> q;
assert(q == 1);
int u1 = -1, v1 = -1;
for(int i = 0; i < q; ++i){
cin >> u1 >> v1;
}
sort(all(edge), [&](pair<int, int> &p1, pair<int, int> &p2){
return min(dist[p1.first], dist[p1.second]) > min(dist[p2.first], dist[p2.second]);
});
ds.init(n + 1);
int ans = -1;
for(int i = 0; i < edge.size(); ++i){
ds.unite(edge[i].first, edge[i].second);
if(ds.connected(u1, v1)){
ans = min(dist[edge[i].first], dist[edge[i].second]);
break;
}
}
cout << ans << "\n";
return 0;
}
