#include <bits/stdc++.h>
#define int long long
using namespace std;
string to_string(string s) { return s; }
template <typename T> string to_string(T v) {
bool first = true;
string res = "[";
for (const auto &x : v) {
if (!first)
res += ", ";
first = false;
res += to_string(x);
}
res += "]";
return res;
}
template <typename A, typename B>
string to_string(pair<A, B> p) {
return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
void dbg_out() { cout << endl; }
template <typename Head, typename... Tail> void dbg_out(Head H, Tail... T) {
cout << ' ' << to_string(H);
dbg_out(T...);
}
#ifdef DEBUG
#define dbg(...) cout << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#else
#define dbg(...)
#endif
struct State {
int source = -1; int target = -1; int distance = 1e18;
State next (int node, int next, int cost) {
State st;
st.source = source == -1 ? next : source;
st.distance = cost + distance;
if (next == target) st.distance = 1e18;
st.target = node;
return st;
}
bool operator< (const State &other) const {
return distance < other.distance;
}
};
const int MAXN = 2010;
struct CNT {
signed dp[MAXN];
signed lp[MAXN];
signed vp[MAXN];
int stage = 1;
CNT () {
for (int i = 0; i < MAXN; i ++)
vp[i] = 0;
}
void clear () {
stage ++;
}
void check (int node) {
if (vp[node] != stage) {
vp[node] = stage;
lp[node] = dp[node];
}
}
int get (int x) {
if (x == -1) return 0;
check(x);
return dp[x] - lp[x];
}
void insert (int x) {
if (x == -1) return ;
check(x);
dp[x] ++;
}
};
string to_string (State state) {
if (state.distance == 1e18)
return "State#";
return "State[" + to_string(state.source + 1) + " => " + to_string(state.target + 1) + ", " + to_string(state.distance) + "]";
}
CNT map_buffer[5000]; int buffer_pos = 0;
CNT* get_buffer () {
assert(buffer_pos < 5000);
return map_buffer + (buffer_pos ++);
}
struct Matrix {
vector<State> pcc;
CNT* lst = get_buffer();
CNT* fst = get_buffer();
set<pair<int, int>> s;
bool append (State state, bool apply = true) {
if (pcc.size() >= 9) return false;
if (lst->get(state.target) >= 3) return false;
if (fst->get(state.source) >= 3) return false;
if (s.find({ state.source, state.target }) != s.end()) return false;
if (apply) {
lst->insert(state.target);
fst->insert(state.source);
pcc.push_back(state);
s.insert({ state.source, state.target });
}
return true;
}
vector<State> all () {
return pcc;
}
int answer () {
return pcc.size() == 0 ? -1 : pcc[0].distance;
}
void clear () {
fst->clear();
lst->clear();
set<pair<int, int>>().swap(s);
}
Matrix merge (Matrix &other) {
Matrix res;
vector<State> all_states;
for (State s1: all()) {
for (State s2: other.all()) {
State s3;
if (s1.target == s2.source) continue ;
s3.source = s1.source;
s3.target = s2.target;
s3.distance = s1.distance + s2.distance;
all_states.push_back(s3);
}
}
sort(all_states.begin(), all_states.end());
for (State s : all_states)
res.append(s);
res.clear();
buffer_pos = 0;
return res;
}
};
string to_string (Matrix matrix) {
return "Mat" + to_string(matrix.all());
}
using vMatrix = vector<Matrix>;
using ti = pair<pair<int, int>, State>;
using pq = priority_queue<ti, vector<ti>, greater<ti>>;
template<typename T>
using grid = vector<vector<T>>;
using idata = vector<int>;
using graph = grid<pair<int, int>>;
int N, M, T, L;
graph roads;
vMatrix dijkstra (int start) {
pq q;
vMatrix matrices(N);
State startState;
startState.distance = 0;
q.push({ { 0, start }, startState });
dbg(start);
while (q.size() != 0) {
const auto data = q.top(); q.pop();
State state = data.second;
int node = data.first.second;
//if (state.distance >= 1e18) continue ;
dbg(node, state.distance);
if (!matrices[node].append( state )) continue ;
for (const auto & road : roads[node]) {
int next = road.first; int cost = road.second;
State nextState = state.next(node, next, cost);
if (!matrices[next].append(nextState, false)) continue ;
q.push({ { nextState.distance, next }, nextState });
}
}
for (Matrix &matrix : matrices)
matrix.clear();
buffer_pos = 0;
return matrices;
}
struct SegTree {
vector<Matrix> tree;
int size, start, height;
SegTree (int _s) {
size = _s;
height = ceil(log2(size));
start = 1 << height;
tree.resize(start << 1);
}
void modify (int node, Matrix mat) {
node += start;
tree[node] = mat;
node >>= 1;
while (node != 0) {
tree[node] = tree[node * 2].merge(tree[node * 2 + 1]);
node >>= 1;
}
}
Matrix query (int right) {
vector<int> queries;
right += start;
int limit = start;
while (limit < right) {
if ((right & 1) == 0) queries.push_back(right);
right = (right - 1) >> 1;
limit = limit >> 1;
}
if (limit == right) queries.push_back(right);
reverse(queries.begin(), queries.end());
Matrix mat = tree[queries[0]];
for (int i = 1; i < queries.size(); i ++)
mat = mat.merge( tree[queries[i]] );
return mat;
}
};
grid<Matrix> matrixGrid;
signed main () {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> N >> M >> T >> L;
roads.resize(N);
for (int i = 0; i < M; i ++) {
int a, b, c;
cin >> a >> b >> c;
a --; b --;
roads[a].push_back({ b, c });
roads[b].push_back({ a, c });
}
for (int i = 0; i < N; i ++)
matrixGrid.push_back( dijkstra(i) );
idata DV(L);
for (int i = 0; i < L; i ++) {
cin >> DV[i];
DV[i] --;
}
SegTree tree(L - 1);
for (int i = 1; i < L; i ++)
tree.modify(i - 1, matrixGrid[DV[i - 1]][DV[i]]);
for (int i = 0; i < T; i ++) {
int p, v;
cin >> p >> v;
p --;
v --;
DV[p] = v;
if (p != 0) tree.modify(p - 1, matrixGrid[DV[p - 1]][DV[p]]);
if (p != L - 1) tree.modify(p, matrixGrid[DV[p]][DV[p + 1]]);
Matrix result = tree.query(L - 2);
int answer = result.answer();
if (answer == 1e18) answer = -1;
cout << answer << "\n";
}
}
