#include <bits/stdc++.h>
using namespace std;
using ll = long long;
struct edge{
int a,b;
ll w;
};
const ll inf=1000000000000000000;
vector<vector<pair<int,ll>>> adj;
int l;
vector<vector<int>> up;
vector<ll> ma;
vector<vector<ll>> mup;
vector<int> tin;
vector<ll> dpt;
vector<int> tout;
int timer=-1;
vector<int> iss;
void ini(int u, int p){
timer++;
tin[u]=timer;
up[u][0]=p;
for(int i=1;i<=l;i++)up[u][i]=up[up[u][i-1]][i-1];
if(iss[u])ma[u]=0;
else ma[u]=inf;
for(auto [v,w]: adj[u]){
if(v!=p){
dpt[v]=dpt[u]+w;
ini(v,u);
ma[u]=min(ma[u],ma[v]+w);
}
}
mup[u][0]=min(ma[p]+dpt[u]-dpt[p],inf);
for(int i=1;i<=l;i++){
mup[u][i]=min(mup[u][i-1],mup[up[u][i-1]][i-1]+dpt[u]-dpt[up[u][i-1]]);
}
timer++;
tout[u]=timer;
}
bool isanc(int u, int v){
if(tin[u]<=tin[v] and tout[u]>=tout[v])return true;
return false;
}
int lca(int u, int v){
if(isanc(u,v))return u;
if(isanc(v,u))return v;
for(int i=l;i>=0;i--){
if(!isanc(up[u][i],v))u=up[u][i];
}
return up[u][0];
}
int main(){
int n,s,q,e;
cin >> n >> s >> q >> e;
e--;
l=ceil(log2(n));
adj.resize(n);
iss.resize(n);
tin.resize(n);
tout.resize(n);
ma.resize(n);
up.resize(n,vector<int>(l+1));
mup.resize(n,vector<ll>(l+1));
vector<edge> edl;
dpt.resize(n);
for(int i=0;i<n-1;i++){
edge c;
cin >> c.a >> c.b >> c.w;
c.a--;
c.b--;
adj[c.a].push_back({c.b,c.w});
adj[c.b].push_back({c.a,c.w});
edl.push_back(c);
}
for(int i=0;i<s;i++){
int x;
cin >> x;
x--;
iss[x]=1;
}
ini(e,e);
while(q--){
int id,u;
cin >> id >> u;
id--;u--;
int rt1=lca(edl[id].a,u);
int rt2=lca(edl[id].b,u);
if(rt1==edl[id].a and rt2==edl[id].b){
if(dpt[rt1]<dpt[rt2])rt1=rt2;
ll ans=ma[u];
int cu=u;
for(int i=l;i>=0;i--){
if(isanc(rt1,up[cu][i])){
ans=min(ans,mup[cu][i]);
cu=up[cu][i];
}
}
if(ans!=inf)cout << ans << "\n";
else cout << "oo\n";
}
else cout << "escape\n";
}
}
