#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> ii;
typedef vector<ii> vi;
const int MAX_N=1e5+10;
const ll MAX=1e15;
vector<vi> G;
int shop[MAX_N];
ll dis[MAX_N];
ll dp[MAX_N];
int pa[MAX_N][22];
ll jump[MAX_N][22];
int level[MAX_N];
void dfs(int u,int p){
if(shop[u]) dp[u]=0;
for(auto &v:G[u]){
if(v.first!=p){
dis[v.first]=dis[u]+v.second;
dfs(v.first,u);
dp[u]=min(dp[u], dp[v.first]+v.second);
}
}
}
void jumping(int u,int p){
pa[u][0]=p;
jump[u][0]=dp[p]+dis[u]-dis[p];
for(int i=1;i<20;i++){
pa[u][i]=pa[pa[u][i-1]][i-1];
jump[u][i]=min({
dp[pa[u][i]]+dis[u]-dis[pa[u][i]],
jump[u][i-1],
jump[pa[u][i-1]][i-1]+dis[u]-dis[pa[u][i-1]]
});
}
for(auto &v:G[u]){
if(v.first!=p){
level[v.first]=level[u]+1;
jumping(v.first, u);
}
}
}
int lca(int u,int v){
if(level[v]>level[u])
swap(v,u);
int d=level[u]-level[v];
for(int i=0;i<20;i++){
if(d&(1<<i))
u=pa[u][i];
}
if(u==v) return u;
for(int i=19;i>=0;i--){
if(pa[u][i]!=pa[v][i]){
u=pa[u][i];
v=pa[v][i];
}
}
return pa[u][0];
}
ll getShop(int start,int end){
ll ans=dp[start];
int d=level[start]-level[end];
int u=start;
for(int i=0;i<20;i++){
if(d&(1<<i)){
ll rp=jump[u][i]+dis[start]-dis[u];
ans=min(ans,rp);
u=pa[u][i];
}
}
return ans;
}
int main(){
int n,s,q,e; cin>>n>>s>>q>>e;
G.resize(n+1);
vector<ii> edges;
for(int i=0;i<n-1;i++){
int a,b,w; cin>>a>>b>>w;
G[a].push_back(ii(b,w));
G[b].push_back(ii(a,w));
edges.push_back(ii(a,b));
}
for(int i=0;i<s;i++){
int a; cin>>a;
shop[a]=1;
}
dis[e]=0;
for(int i=1;i<=n;i++)
dp[i]=MAX;
dfs(e,e);
jumping(e,e);
while(q--){
int bl, st;
cin>>bl>>st;
bl--;
int lo=(level[edges[bl].first]>level[edges[bl].second])?
edges[bl].first:
edges[bl].second;
if(lca(st,lo)==lo){
ll ans=getShop(st, lo);
if(ans>=MAX) cout<<"oo\n";
else cout<<ans<<'\n';
}
else{
cout<<"escaped\n";
}
}
}
