#include <bits/stdc++.h>
using namespace std;
#define int long long int
#define ins insert
#define pb push_back
#define endl '\n'
#define putr(x) cout<<x<<endl;return;
#define all(x) x.begin(),x.end()
int nxt(){ int x;cin>>x; return x; }
const int mod = 1e9 +7, sze = 1e5 +10, inf = INT_MAX, LG = 20;
pair<int,int> edge[sze];
int sp[sze];
vector<pair<int,int>> graph[sze];
int timer =1;
int gir[sze];
int cix[sze];
int up[LG][sze];
int dp[LG][sze];
int as[sze];
int dist[sze];
int depth[sze];
void dfs(int node,int par=0){
if(sp[node]){
as[node]=0;
}
gir[node]=++timer;
up[0][node]=par;
for(int i =1;i<LG;i++){
up[i][node]=up[i-1][up[i-1][node]];
}
for(auto [v,w]:graph[node]){
if(v!=par){
depth[v]=depth[node]+1;
dist[v]=dist[node] + w;
dfs(v,node);
as[node]=min(as[node],as[v] + w);
}
}
cix[node]=++timer;
}
void dps(int node,int par=0){
if(as[node]!=inf){
dp[0][node]= -dist[node] + as[node];
}
if(as[ up[0][node] ]!=inf){
dp[0][node]= min(dp[0][node], -dist[ up[0][node] ] + as[ up[0][node] ]);
}
for(int i =1;i<LG;i++){
dp[i][node]=min(dp[i-1][node], dp[i-1][ up[i-1][node] ]);
}
for(auto [v,w]:graph[node]){
if(v!=par){
dps(v,node);
}
}
}
int in(int u,int v){
return (gir[v]<=gir[u] && cix[v]>=cix[u]);
}
int lca(int u,int v){
if(in(u,v)){
return v;
}
if(in(v,u)){
return u;
}
for(int i = LG-1;i>=0;i--){
if(!in( up[i][u],v )){
u = up[i][u];
}
}
return up[0][u];
}
int qry(int u,int v){
int res=inf;
if(as[u]!=inf){
res=as[u] - dist[u];
}
for(int i =LG-1;i>=0;i--){
if(depth[u] - (1<<i) >= depth[v]){
res=min(res, dp[i][u]);
u = up[i][u];
}
}
return res;
}
void fast(){
int n,s,q,root,x;
cin>>n>>s>>q>>root;
for(int i=0;i<=n;i++){
as[i]=inf;
dp[i][0]=inf;
}
for(int i =1;i<=n-1;i++){
int u,v,w;
cin>>u>>v>>w;
edge[i]={u,v};
graph[u].pb({v,w});
graph[v].pb({u,w});
}
for(int i=1;i<=s;i++){
cin>>x;
sp[x]=1;
}
dfs(root);
dps(root);
while(q--){
int idx, u ;
cin>>idx>>u;
auto[ k,v ] = edge[idx];
if(depth[k]<depth[v]){
swap(k,v);
}
if(lca(u,k)!=k){
cout<<"escaped"<<endl;
}
else{
// cout<<"-1"<<endl;
int res = qry(u,k) + dist[u];
if(res<=inf){
cout<<res<<endl;
}
else{
cout<<"oo"<<endl;
}
}
}
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tt = 1;
// cin>>tt;
while(tt--){
fast();
}
return 0;
}
