#include <bits/stdc++.h>
using namespace std;
#define FOR(i, l, r) for(int i = (l); i < (r); ++i)
#define ROF(i, r, l) for(int i = (r) - 1; i >= (l); --i)
#define mp make_pair
#define mt make_tuple
#define ff first
#define ss second
#define all(v) begin(v), end(v)
#define rall(v) rbegin(v), rend(v)
#define sz(v) (int)v.size()
#define compact(v) v.erase(unique(all(v)), end(v))
#define pb push_back
#define eb emplace_back
#define readFile(task) freopen(task, "r", stdin)
#define writeFile(task) freopen(task, "w", stdout)
#define dbg(x) "[" #x " = " << (x) << "]"
template<typename T>
bool minimize(T& a, const T& b){
if(a > b) return a = b, true;
return false;
}
template<typename T>
bool maximize(T& a, const T& b){
if(a < b) return a = b, true;
return false;
}
using ll = long long;
using db = double;
using str = string;
using ull = unsigned long long;
using ldb = long double;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vl = vector<ll>;
using vb = vector<bool>;
using vc = vector<char>;
using vs = vector<str>;
using vpi = vector<pi>;
using vpl = vector<pl>;
using vpd = vector<pd>;
using vvi = vector<vi>;
using vvl = vector<vl>;
void setIO(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
readFile("task.inp");
writeFile("task.out");
#endif // LOCAL
}
template<typename T, typename U>
ostream& operator << (ostream& out, pair<T, U> p){
return out << '(' << p.ff << ',' << p.ss << ')';
}
void testcase(){
int N, M, T, L;
cin >> N >> M >> T >> L;
vector<vector<tuple<int, int, int>>> adj(N);
vvi idx(N, vi(M, -1));
int nn = 0;
vpi e(2 * M);
FOR(i, 0, M){
int u, v, w;
cin >> u >> v >> w;
--u, --v;
adj[u].eb(v, i, w);
adj[v].eb(u, i, w);
e[idx[u][i] = nn++] = mp(u, i);
e[idx[v][i] = nn++] = mp(v, i);
}
const ll inf = 1e18;
using node = tuple<ll, int, int>;
priority_queue<node, vector<node>, greater<node>> pq;
auto dijkstra1 = [&](int p){
vl d(nn, inf);
d[p] = 0;
// cout << dbg(e[p]) << '\n';
pq.push(mt(0, e[p].ff, e[p].ss));
while(!pq.empty()){
ll dist; int u, pre; tie(dist, u, pre) = pq.top(); pq.pop();
if(d[idx[u][pre]] != dist) continue;
// cout << dbg(u) << dbg(pre) << dbg(dist) << '\n';
for(auto &[v, id, w] : adj[u]) if(id != pre){
if(d[idx[v][id]] > dist + w){
d[idx[v][id]] = dist + w;
pq.push(mt(d[idx[v][id]], v, id));
}
}
}
// cout << '\n';
return d;
};
auto dijkstra2 = [&](int s){
vl d(nn, inf);
for(auto [t, id, w] : adj[s]){
d[idx[t][id]] = w;
pq.push(mt(w, t, id));
}
// cout << dbg(s) << '\n';
while(!pq.empty()){
ll dist; int u, pre; tie(dist, u, pre) = pq.top(); pq.pop();
if(d[idx[u][pre]] != dist) continue;
// cout << dbg(u) << dbg(pre) << dbg(dist) << '\n';
for(auto &[v, id, w] : adj[u]) if(id != pre){
if(d[idx[v][id]] > dist + w){
d[idx[v][id]] = dist + w;
pq.push(mt(d[idx[v][id]], v, id));
}
}
}
// cout << '\n';
return d;
};
vvl dists(nn);
FOR(i, 0, nn){
dists[i] = dijkstra1(i);
}
vvl free_start_dists(N);
FOR(i, 0, N){
free_start_dists[i] = dijkstra2(i);
}
vi X(L);
FOR(i, 0, L) cin >> X[i], --X[i];
auto solve = [&](){
vl dp(nn, inf);
// FOR(i, 0, L) cout << X[i] << ' '; cout << '\n';
for(auto &[v, id, w] : adj[X[1]]){
minimize(dp[idx[X[1]][id]], free_start_dists[X[0]][idx[X[1]][id]]);
// cout << dbg(X[1]) << dbg(id) << dbg(dp[idx[X[1]][id]]) << '\n';
}
FOR(i, 2, L){
vl nw(nn, inf);
for(auto &[v, idv, _] : adj[X[i]]){
int t = idx[X[i]][idv];
for(auto &[u, idu, __] : adj[X[i-1]]){
int s = idx[X[i-1]][idu];
minimize(nw[t], dp[s] + dists[s][t]);
// cout << dbg(nw[t]) << dbg(t) << dbg(e[s]) << dbg(e[t]) << dbg(dp[s] + dists[s][t]) << '\n';
}
}
swap(nw, dp);
}
ll res = *min_element(all(dp));
if(res == inf) res = -1;
return res;
};
while(T--){
int P, Q;
cin >> P >> Q;
--P, --Q;
X[P] = Q;
cout << solve() << '\n';
}
}
int main(){
setIO();
int T = 1;
// cin >> T;
while(T--) testcase();
return 0;
}
