#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define lll __ll128
#define sza(x) ((ll)x.size())
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define pll pair<ll,ll>
#ifdef DEBUG
#include "helper.h"
#else
#define dbg(...)
#endif
#define log(a) 63-__builtin_clzll(a)
const ll INF=1e18;
const ll MOD=1e9+7;
void solve() {
int n,s,q,e;
cin>>n>>s>>q>>e;
e--;
vector<vector<pair<int,ll>>> edges(n);
vector<pair<int,int>> all_edges;
set<int> shops;
for(int i=0;i<n-1;i++){
int a,b;
ll c;
cin>>a>>b>>c;
a--,b--;
all_edges.push_back({a,b});
edges[a].push_back({b,c});
edges[b].push_back({a,c});
}
for(int i=0;i<s;i++){
int a;
cin>>a;
a--;
shops.insert(a);
}
int LOG=__lg(n);
vector<vector<pair<int,ll>>> bj(n,vector<pair<int,ll>>(LOG+1,{-1,LLONG_MAX}));
vector<int> depth(n);
vector<ll> cost(n);
vector<ll> dp(n,LLONG_MAX);
dbg(dp);
dbg(edges);
auto build=[&](auto && build, int u,int p,int _depth,ll _cost ) -> void {
cost[u]=_cost;
depth[u]=_depth;
bj[u][0].first=p;
if(shops.contains(u)){
dp[u]=0;
}
// dbg(u,p);
for(auto nei:edges[u]){
if(nei.first==p)continue;
build(build,nei.first,u,_depth+1,_cost+nei.second);
if(dp[nei.first]!=LLONG_MAX)
dp[u]=min(dp[u],nei.second+dp[nei.first]);
}
};
build(build,e,-1,0,0);
dbg(1);
for(int i=0;i<n;i++){
bj[i][0].second=min(-cost[bj[i][0].first]+dp[bj[i][0].first],-cost[i]+dp[i]);
}
for(int log=1;log<=LOG;log++){
for(int i=0;i<n;i++){
auto [v,cost]=bj[i][log-1];
if(v!=-1){
bj[i][log].first=bj[v][log-1].first;
bj[i][log].second=min(bj[v][log-1].second,bj[i][log-1].second);
}
}
}
auto get_ans=[&](int v,int num) -> pair<int,ll> {
int curr=v;
ll curr_cost=-cost[v]+dp[v];
for(int i=0;i<=LOG;i++){
if(num&(1<<i)){
curr_cost=min(curr_cost,bj[curr][i].second);
curr=bj[curr][i].first;
}
if(curr==-1)return {-1,LLONG_MAX};;
}
return {curr,curr_cost+cost[v]};
};
while(q--){
int index;
int v;
cin>>index>>v;
index--,v--;
auto [_p,_q]=all_edges[index];
dbg(v);
if(depth[_q]<depth[_p])swap(_p,_q);
dbg(get_ans(v,-depth[_q]+depth[v]),depth[_q]-depth[v]);
if(get_ans(v,-depth[_q]+depth[v]).first!=_q){
cout<<"escaped"<<endl;
}else{
auto [_v,ans]=get_ans(v,-depth[_q]+depth[v]);
if(ans==LLONG_MAX){
cout<<"oo"<<endl;
}else{
cout<<ans<<endl;
}
}
}
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("cbarn2.in","r",stdin);
// freopen("cbarn2.out","w",stdout);
// cout<<1<<endl;
// dbg(deals);
// ll t;
// cin>>t;
// while(t--)
solve();
}
