#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#define vi vector<int>
#define ve vector
#define ll long long
#define vl vector<ll>
#define vll vector<pair<ll,ll>>
#define onbit __builtin_popcount
#define ii pair<int,int>
#define vvi vector<vi>
#define vii vector<ii>
#define gii greater<ii>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define INF 1e18
#define eps 1e-7
#define eps1 1e-2
#define optimise ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define MAX_A 1e5+5
using namespace std;
using namespace __gnu_pbds;
template <class T>
using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const ll MOD = 1e9+7;
const int nax = 1e5+5;
const int MAX_VAL = 1e6+1;
double PI=3.14159265359;
int arx[8]={1,0,0,-1,-1,-1, 1, 1};
int ary[8]={0,1,-1, 0, 1,-1,-1, 1};
void setIO(string s) {
freopen((s + ".in").c_str(), "r", stdin);
freopen((s + ".out").c_str(), "w", stdout);
}
int n,s,q,e;
vii adj[nax];
bool shop[nax];
long long dp[nax];
long long dis[nax];
pair<int,int> euler[nax];
int timer=-1;
int parent[nax][20];
long long cnt[nax][20];
int depth[nax];
void euler_tour(int x,int p)
{
timer++;
euler[x].fi=timer;
for(auto u:adj[x]){
if(u.fi==p) continue;
depth[u.fi]=depth[x]+1;
dis[u.fi]=dis[x]+u.se;
parent[u.fi][0]=x;
euler_tour(u.fi,x);
}
euler[x].se=timer;
return;
}
void dfs(int x,int p)
{
if(adj[x].size()==1&&x!=e){
if(shop[x]) dp[x]=0;
else dp[x]=1e15;
return;
}
dp[x]=1e15;
for(auto u:adj[x]){
if(u.fi==p) continue;
dfs(u.fi,x);
dp[x]=min(dp[x],dp[u.fi]+u.se);
}
if(shop[x]) dp[x]=0;
return;
}
void jumps(int x,int p)
{
cnt[x][0]=min(dp[x],dp[parent[x][0]]);
for (int i = 1; i < 20; ++i)
{
parent[x][i]=parent[parent[x][i-1]][i-1];
cnt[x][i]=min(cnt[x][i-1],cnt[parent[x][i-1]][i-1]);
//if(x==0) cout <<cnt[x][i]<<" "<<cnt[x][i-1]<<" "<<cnt[parent[x][i-1]][i-1]<<" "<<parent[x][i]<<endl;
}
//if(x==9) for(auto u:adj[x]) cout <<u.fi<<endl;
for(auto u:adj[x]){
if(u.fi==p) continue;
jumps(u.fi,x);
}
}
int main(){
optimise;
/*#ifndef ONLINE_JUDGE
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif*/
cin>>n>>s>>q>>e;
e--;
parent[e][0]=e;
dis[e]=0;
depth[e]=0;
pair<int,int> edges[n-1];
for (int i = 0; i < n-1; ++i)
{
int x,y,z;
cin>>x>>y>>z;
x--;y--;
edges[i]={x,y};
adj[x].pb({y,z});
adj[y].pb({x,z});
}
euler_tour(e,-1);
for (int i = 0; i < s; ++i)
{
int x;
cin>>x;
x--;
shop[x]=true;
}
dfs(e,-1);
for (int i = 0; i < n; ++i)
{
dp[i]-=dis[i];
}
jumps(e,-1);
while(q--){
int i,r;
cin>>i>>r;
i--,r--;
int a=edges[i].fi;
int b=edges[i].se;
if(euler[a].fi>euler[b].fi) swap(a,b);
//cout <<euler[b].fi<<" "<<euler[b].se<<" "<<euler[r].fi<<endl;
if(euler[b].fi<=euler[r].fi&&euler[r].se<=euler[b].se){
int d=depth[r]-depth[b];
//cout <<dp[r]<<" "<<dis[r]<<endl;
long long res=dp[r];
int lst=r;
//cout <<d<<endl;
for (int i = 19; i >= 0; --i)
{
if(d&(1<<i)){
res=min(res,cnt[lst][i]);
lst=parent[lst][i];
}
}//cout <<res<<" "<<lst<<endl;
if(shop[r]){
cout <<0<<endl;
}
else if(res>=1e14){
cout <<"oo"<<endl;
}else{
//cout <<res<<" "<<dis[r]-dis[b]+1<<endl;
cout<<dis[r]+res<<endl;
}
}else cout <<"escaped"<<endl;
}
}
