#include <iostream>
#include <bits/stdc++.h>
using namespace std;
const long long MAXN = 1e5+5;
vector<pair<long long,long long>> v1[MAXN];
long long h[MAXN];
long long cities[MAXN];
long long distroot[MAXN];
long long p[MAXN];
long long dp[MAXN][25];
long long nearest[MAXN];
long long dp2[MAXN][25];
vector<pair<long long,long long>> edges;
void dfs(long long curr,long long par){
//cout<<curr<<endl;
if(curr!=par){
h[curr] = h[par]+1;
}
if(cities[curr]){
nearest[curr] = 0;
}else{
nearest[curr] = 1e18;
}
p[curr] = par;
dp[curr][0] = par;
for(auto x:v1[curr]){
if(x.first!=par){
distroot[x.first] = distroot[curr]+ x.second;
dfs(x.first,curr);
nearest[curr] = min(nearest[curr],nearest[x.first]+x.second);
}
}
for(auto x:v1[curr]){
if(x.first!=par){
dp2[x.first][0] = min(nearest[x.first],nearest[curr]+x.second);
}
}
}
bool isanc(long long x,long long y){
for(long long j=20;j>=0;j--){
if(h[dp[x][j]]>=h[y]){
x = dp[x][j];
}
}
return x == y;
}
long long dist(long long x,long long y){
return distroot[x]-distroot[y];
}
long long jump(long long x,long long y){
long long ans = nearest[x];
long long og = x;
for(long long j=20;j>=0;j--){
if(h[dp[x][j]]>=h[y]){
ans = min(ans,dp2[x][j]+dist(og,x));
//cout<<x<<" "<<dp2[x][j]<<endl;
x = dp[x][j];
//cout<<ans<<endl;
}
}
return ans;
}
int main() {
long long n,s,q,e;
edges.push_back(make_pair(0,0));
cin>>n>>s>>q>>e;
for(long long i=1;i<n;i++){
long long x,y,w;
cin>>x>>y>>w;
v1[x].push_back(make_pair(y,w));
v1[y].push_back(make_pair(x,w));
edges.push_back(make_pair(x,y));
}
for(long long i=1;i<=s;i++){
long long x;
cin>>x;
cities[x] = 1;
}
for(long long i=0;i<=20;i++){
for(long long j=1;j<=n;j++){
dp[j][i] = -1;
dp2[j][i] = 1e18;
}
}
dfs(e,e);
for(long long i=1;i<=n;i++){
// cout<<dp2[i][0]<<endl;
}
for(long long i=1;i<=20;i++){
for(long long j=1;j<=n;j++){
if(dp[j][i-1] == -1){
dp[j][i] = -1;
}else{
dp[j][i] = dp[dp[j][i-1]][i-1];
}
}
}
for(long long i=1;i<=20;i++){
for(long long j=1;j<=n;j++){
if(dp[j][i-1] == -1){
dp2[j][i] = 1e18;
}else{
dp2[j][i] = min(dp2[j][i-1],dp2[dp[j][i-1]][i-1]+dist(j,dp[j][i-1]));
}
}
}
while(q--){
long long ind,r;
cin>>ind>>r;
long long x = edges[ind].first;
long long y = edges[ind].second;
if(h[x]>h[y]){
swap(x,y);
}
if(isanc(r,x) && isanc(r,y)){
if(jump(r,y) == 1e18){
cout<<"oo"<<endl;
}else{
cout<<jump(r,y)<<endl;
}
}else{
cout<<"escaped"<<endl;
}
}
}
