#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int nx=1e5+5;
ll n, s, q, e, u, v, w, mn[nx], ans[nx], x, y;
vector<tuple<int, int, int>> d[nx];
vector<pair<int, int>> t[nx];
bool pw[nx], dp[nx];
void dfs(int u, int p)
{
for (auto [v, w, i]:d[u])
{
if (v==p) continue;
dfs(v, u);
mn[u]=min(mn[u], mn[v]+w);
}
if (pw[u]) mn[u]=0;
}
void dfs2(int u, int p)
{
for (auto [x, y]:t[u]) ans[y]=dp[x]?mn[u]:-1;
for (auto [v, w, i]:d[u])
{
if (v==p) continue;
dp[i]=1;
dfs2(v, u);
dp[i]=0;
}
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n>>s>>q>>e;
for (int i=1; i<=n-1; i++) cin>>u>>v>>w, d[u].push_back({v, w, i}), d[v].push_back({u, w, i});
for (int i=1; i<=n; i++) mn[i]=1e18;
for (int i=0; i<s; i++) cin>>x, pw[x]=1;
for (int i=0; i<q; i++) cin>>x>>y, t[y].push_back({x, i});
dfs(e, e);
dfs2(e, e);
for (int i=0; i<q; i++)
{
//cout<<"here"<<' '<<ans[i]<<'\n';
if (ans[i]==-1) cout<<"escaped\n";
else if (ans[i]==1e18) cout<<"oo\n";
else cout<<ans[i]<<'\n';
}
}
