#include<bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
int n,s,q,e;
vector<pair<int,int>> con[100005];
pair<int,int> edges[100005];
int tin[100005],tout[100005],timer;
bool iss[100005];
long long depth[100005];
long long mindist[100005];
int anc[1000005][17];
long long min_anc[1000005][17];
void dfs(int nod, int par)
{
tin[nod]=++timer;
mindist[nod]=INF;
if(iss[nod]) mindist[nod]=0;
for(auto [adj,c]:con[nod])
{
if(adj!=par)
{
anc[adj][0]=nod;
depth[adj] = depth[nod]+c;
dfs(adj,nod);
mindist[nod] = min(mindist[nod], mindist[adj]+c);
}
}
//cout<<nod<<" "<<mindist[nod]<<" mindist\n";
min_anc[nod][0] = mindist[nod] - depth[nod];
if(mindist[nod]==INF) min_anc[nod][0]=INF;
tout[nod]=++timer;
}
bool isanc(int x, int y)
{
if(tin[x]<=tin[y] && tout[x]>=tout[y])
return 1;
return 0;
}
long long calc_min(int nod, int lim)
{
long long aux=INF;
//cout<<nod<<" "<<lim<<" calc_min\n";
for(int p=16;p>=0;p--)
{
if(!isanc(anc[nod][p],lim))
{
aux = min(aux, min_anc[nod][p]);
nod = anc[nod][p];
}
}
aux = min(aux, min_anc[nod][0]);
return aux;
}
signed main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
cin>>n>>s>>q>>e;
int u,v,w;
for(int i=1;i<n;i++)
{
cin>>u>>v>>w;
con[u].push_back({v,w});
con[v].push_back({u,w});
edges[i] = {u,v};
}
for(int i=1;i<=s;i++)
{
cin>>u;
iss[u]=1;
}
dfs(e,-1);
anc[e][0]=e;
for(int p=1;p<17;p++)
{
for(int i=1;i<=n;i++)
{
anc[i][p] = anc[anc[i][p-1]][p-1];
min_anc[i][p] = min(min_anc[i][p-1], min_anc[anc[i][p-1]][p-1]);
}
}
for(int i=1;i<n;i++)
if(anc[edges[i].first][0] == edges[i].second)
swap(edges[i].first, edges[i].second);
while(q--)
{
cin>>u>>v;
if(isanc(edges[u].second,v))
{
long long x = calc_min(v,edges[u].first);
if(x>=INF) cout<<"oo\n";
else cout<<x+depth[v]<<"\n";
}
else
{
cout<<"escaped\n";
}
}
return 0;
}
