#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int LOG = 17;
const int can = 350;
int n,q,numshop,root;
int shop[100009];
vector <pair <int,int>> adj[100009];
struct {
int u,v,w;
} edge[100009];
int h[100009];
long long depth[100009];
int tin[100009],tout[100009],timedfs;
int pos[100009],timelca,R[200009][LOG + 1];
void dfs(int node,int par) {
tin[node] = ++timedfs;
pos[node] = ++timelca;
R[timelca][0] = node;
for (auto x : adj[node]) if (x.first != par) {
int ver = x.first,w = x.second;
h[ver] = h[node] + 1;
depth[ver] = depth[node] + w;
dfs(ver,node);
R[++timelca][0] = node;
}
tout[node] = timedfs;
}
bool intree(int child,int anc) {
return tin[anc] <= tin[child] && tout[child] <= tout[anc];
}
void buildsparse() {
for (int j = 1;j <= LOG;j++) {
for (int i = 1;i + (1 << j) - 1 <= timelca;i++) {
int d1 = R[i][j - 1],d2 = R[i + (1 << (j - 1))][j - 1];
R[i][j] = (h[d1] < h[d2] ? d1 : d2);
}
}
}
int lca(int u,int v) {
u = pos[u],v = pos[v];
if (u > v) swap(u,v);
int i = __lg(v - u + 1);
int d1 = R[u][i],d2 = R[v - (1 << i) + 1][i];
return (h[d1] < h[d2] ? d1 : d2);
}
long long dis(int u,int v) {
return depth[u] + depth[v] - 2*depth[lca(u,v)];
}
struct {
int l,r;
long long mindis[100009];
} block[can + 1];
void djt(vector <int> start,long long l[]) {
for (int i = 1;i <= n;i++) l[i] = 1e18;
priority_queue <pair<ll,int>,vector <pair <ll,int>>,greater <pair <ll,int>>> pq;
for (auto x : start) {
l[x] = 0;
pq.push({l[x],x});
}
while (pq.size()) {
int ver = pq.top().second;
long long cost = pq.top().first;
pq.pop();
if (l[ver] < cost) continue;
for (auto x : adj[ver]) {
int u = x.first,w = x.second;
if (l[u] > l[ver] + w) {
l[u] = l[ver] + w;
pq.push({l[u],u});
}
}
}
}
void precal() {
sort(shop + 1,shop + 1 + numshop,[] (int a,int b) {
return tin[a] < tin[b];
});
for (int id = 0;;id++) {
block[id].l = max(1,id*can);
block[id].r = min(numshop,(id + 1)*can - 1);
vector <int> start;
for (int i = block[id].l;i <= block[id].r;i++) start.push_back(shop[i]);
djt(start,block[id].mindis);
if (block[id].r == numshop) break;
}
}
long long calc(int l,int r,int vertice) {
if (l > r) return 1e18;
long long ret = 1e18;
int lid = l/can,rid = r/can;
if (lid == rid) {
for (int i = l;i <= r;i++) ret = min(ret,dis(vertice,shop[i]));
return ret;
}
for (int i = l;i <= block[lid].r;i++) ret = min(ret,dis(vertice,shop[i]));
for (int i = lid + 1;i < rid;i++) ret = min(ret,block[i].mindis[vertice]);
for (int i = block[rid].l;i <= r;i++) ret = min(ret,dis(vertice,shop[i]));
return ret;
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
// freopen(".inp","r",stdin);
// freopen(".out","w",stdout);
cin >> n >> numshop >> q >> root;
for (int i = 1;i < n;i++) {
int u,v,w;cin >> u >> v >> w;
adj[u].push_back({v,w});
adj[v].push_back({u,w});
edge[i] = {u,v,w};
}
for (int i = 1;i <= numshop;i++) {
cin >> shop[i];
}
dfs(root,-1);
buildsparse();
for (int i = 1;i < n;i++) if (h[edge[i].u] > h[edge[i].v]) swap(edge[i].u,edge[i].v);
precal();
while (q--) {
int vertice,_;cin >> _ >> vertice;
int child = edge[_].v;
//check escape
if ((intree(vertice,child) ^ intree(root,child)) == 0) {
cout << "escaped\n";
continue;
}
//tim khong trong shop ma cay con goc child quan ly
int l,r;
int low = 1,high = numshop;
while (low <= high) {
int mid = (low + high) >> 1;
if (tin[shop[mid]] >= tin[child]) high = mid - 1;
else low = mid + 1;
}
l = low;
low = 1,high = numshop;
while (low <= high) {
int mid = (low + high) >> 1;
if (tin[shop[mid]] <= tout[child]) low = mid + 1;
else high = mid - 1;
}
r = high;
long long ret = 1e18;
//TH1: vertice nam trong cay con goc child
if (intree(vertice,child)) {
ret = calc(l,r,vertice);
}
//TH2: vertice khong nam trong cay con goc v
else {
ret = min(calc(1,l - 1,vertice),calc(r + 1,n,vertice));
}
if (ret == 1e18) cout << "oo\n";
else cout << ret << '\n';
}
}
