#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 pb push_back
#define eb emplace_back
#define sz(v) (int)v.size()
#define sum_of(v) accumulate(all(v), 0ll)
#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 ld = long double;
using ull = unsigned long long;
using pi = pair<int, int>;
using pl = pair<ll, ll>;
using pd = pair<db, db>;
using vi = vector<int>;
using vb = vector<bool>;
using vc = vector<char>;
using vl = vector<ll>;
using vd = vector<db>;
using vpi = vector<pi>;
using vpl = vector<pl>;
void setIO(){
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef LOCAL
freopen("task.inp", "r", stdin);
freopen("task.out", "w", stdout);
#endif // LOCAL
}
const int MAX = 1e5 + 5;
const ll inf = 1e18;
using dijkstra_node = tuple<ll, int, int, int>;
struct path{
int s, t; ll dist;
path(int s, int t, ll dist) : s(s), t(t), dist(dist) {}
bool operator < (const path& o) const {
return dist < o.dist;
}
};
const int KEEP = 5;
struct info{
vector<path> paths;
info() : paths() {}
void clear(){
paths.clear();
}
bool insert(const path& p){
if(sz(paths) >= KEEP) return false;
bool equal_s = false, equal_t = false;
FOR(i, 0, sz(paths)){
if(paths[i].s == p.s && paths[i].t == p.t) return false;
if(paths[i].s == p.s){
if(equal_s) return false;
equal_s = true;
}
if(paths[i].t == p.t){
if(equal_t) return false;
equal_t = true;
}
}
paths.pb(p);
return true;
}
ll get(){
if(paths.empty()) return -1;
return paths[0].dist;
}
void debug(){
FOR(i, 0, sz(paths)){
cout << '(' << paths[i].s << ' ' << paths[i].t << ' ' << paths[i].dist << ")\n";
}
}
} options[2000][2000], st[MAX << 2];
int X[MAX];
void pull(info& result, const info& a, const info& b){
result.clear();
vector<path> cur;
FOR(i, 0, sz(a.paths)){
FOR(j, 0, sz(b.paths)){
if(a.paths[i].t != b.paths[j].s){
cur.pb(path(a.paths[i].s, b.paths[j].t, a.paths[i].dist + b.paths[j].dist));
}
}
}
sort(all(cur));
FOR(i, 0, sz(cur)){
result.insert(cur[i]);
}
}
void refine(int id, int l, int r, int u, int v){
if(l == r){
st[id] = options[X[l]][X[l+1]];
} else{
int mid = l + r >> 1;
if(u <= mid) refine(id << 1, l, mid, u, v);
if(mid < v) refine(id << 1 | 1, mid + 1, r, u, v);
pull(st[id], st[id << 1], st[id << 1 | 1]);
}
}
int main(){
setIO();
int N, M, T, L;
cin >> N >> M >> T >> L;
int cnt = 0;
vector<vi> idx(N, vi(N, -1));
vector<vpi> adj(N);
vpi e(M * 2);
FOR(i, 0, M){
int u, v, w;
cin >> u >> v >> w;
--u, --v;
adj[u].eb(v, w);
adj[v].eb(u, w);
assert(idx[u][v] == -1 && idx[v][u] == -1);
e[idx[u][v] = cnt++] = mp(u, v);
e[idx[v][u] = cnt++] = mp(v, u);
}
FOR(i, 0, L) cin >> X[i], --X[i];
priority_queue<dijkstra_node, vector<dijkstra_node>, greater<dijkstra_node>> pq;
FOR(s, 0, N){
for(auto [v, w] : adj[s]){
pq.push(mt(w, v, s, v));
}
vi cnt(N);
while(!pq.empty()){
ll dist; int a, b, u;
tie(dist, a, b, u) = pq.top(); pq.pop();
if(!options[s][u].insert(path(a, b, dist))) continue;
for(auto [v, w] : adj[u]) if(v != b){
pq.push(mt(dist + w, a, u, v));
}
}
}
// cout << X[53] << ' ' << X[54] << '\n';
// cout << st[1].get() << '\n';
// return 0;
// FOR(i, 0, L) cout << X[i] << ' '; cout << '\n';
// cout << dbg(X[52]) << dbg(X[53]) << dbg(X[54]) << '\n';
// options[1][2].debug();
// cout << '\n' << '\n';
while(T--){
int P, Q;
cin >> P >> Q;
--P, --Q;
X[P] = Q;
assert(X[0] != X[1]);
info cur = options[X[0]][X[1]];
FOR(i, 1, L-1){
info nw;
pull(nw, cur, options[X[i]][X[i+1]]);
swap(nw, cur);
assert(X[i] != X[i+1]);
// if(i == L-3){
// cur.debug();
// cout << '\n';
// }
}
// FOR(i, 0, L) cout << X[i] << ' '; cout << '\n';
// cur.debug();
cout << cur.get() << '\n';
}
return 0;
}
