#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<ll,int>
#define X first
#define Y second
const int N=1e5+5;
const int K=22;
const ll oo=(long double)1e18+1;
int n,request,s,e,h,x,y,z,save,temp,timer; ll res;
int a[N],b[N],in[N],out[N],H[N],p[N][K]; ll dist[N],mi[N][K];
bool HasShop[N];
vector <pii> adj[N];
bool yInSubtreex(int x,int y)
{
return in[x]<=in[y] and out[y]<=out[x];
}
void pre_dfs(int u,int par)
{
in[u]=++timer;
if (HasShop[u]) mi[u][0]=dist[u];
else mi[u][0]=oo;
for (pii v:adj[u])
if (v.Y!=par)
{
H[v.Y]=H[u]+1;
dist[v.Y]=dist[u]+v.X;
p[v.Y][0]=u;
pre_dfs(v.Y,u);
mi[u][0]=min(mi[u][0],mi[v.Y][0]+2*dist[v.Y]);
}
if (mi[u][0]!=oo) mi[u][0]-=2*dist[u];
out[u]=timer;
}
ll lift_getmin(int x,int k)
{
ll ans_mi=oo;
for (int j=0;j<=h;j++)
if (k&(1<<j))
{
ans_mi=min(ans_mi,mi[x][j]);
x=p[x][j];
}
return ans_mi;
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> s >> request >> e;
for (int i=1;i<n;i++)
{
cin >> x >> y >> z;
adj[x].push_back(make_pair(z,y));
adj[y].push_back(make_pair(z,x));
a[i]=x;
b[i]=y;
}
for (int i=1;i<=s;i++)
{
cin >> x;
HasShop[x]=true;
}
H[e]=1;
dist[e]=0;
timer=0;
pre_dfs(e,-1);
for (int i=1;i<n;i++)
if (H[a[i]]>H[b[i]]) swap(a[i],b[i]);
h=31-__builtin_clz(n);
for (int j=1;j<=h;j++)
for (int i=1;i<=n;i++)
{
p[i][j]=p[p[i][j-1]][j-1];
mi[i][j]=min(mi[i][j-1],mi[p[i][j-1]][j-1]);
}
while (request--)
{
cin >> save >> y;
x=b[save];
if (yInSubtreex(x,y))
{
temp=H[y]-H[x];
res=lift_getmin(y,temp+1);
if (res==oo) cout << "oo" << '\n';
else cout << res+dist[y] << '\n';
}
else cout << "escaped" << '\n';
}
}
