//dau tuyen
//dau tuyen
//dau tuyen
#pragma GCC optimize ("O2")
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define endl '\n'
#define task "task"
#define task "task"
#define prll pair<ll,ll>
#define pb push_back
#define ld long double
const ll MIN=-1e18,MAX=1e18,MOD=1e9+7,nmax=1e5+5;
ll cost[nmax],f[nmax],mn[nmax][25];
int h[nmax],up[nmax][25];
vector<pair<int,ll>> a[nmax];
bool str[nmax];
vector<pair<int,int>> edge;
void dfs(int u,int par)
{
for(auto i:a[u])
{
if(i.fi!=par)
{
cost[i.fi]=cost[u]+i.se;
h[i.fi]=h[u]+1;
dfs(i.fi,u);
}
}
}
void dfs2(int u,int par)
{
f[u]=MAX;
if(str[u]) f[u]=cost[u];
for(auto i:a[u])
{
if(i.fi!=par)
{
dfs2(i.fi,u);
f[u]=min(f[u],f[i.fi]);
}
}
}
void dfs3(int u,int par)
{
for(auto i:a[u])
{
if(i.fi!=par)
{
up[i.fi][0]=u;
mn[i.fi][0]=f[u]-2*cost[u];
for(int j=1;j<=20;j++)
{
up[i.fi][j]=up[up[i.fi][j-1]][j-1];
mn[i.fi][j]=min(mn[i.fi][j-1],mn[up[i.fi][j-1]][j-1]);
}
dfs3(i.fi,u);
}
}
}
int main(){
#ifndef ONLINE_JUDGE
freopen (task".inp", "r", stdin);
freopen (task".out", "w", stdout);
#endif
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int n,s,q,e;
cin>>n>>s>>q>>e;
edge.push_back({0,0});
for(int i=1;i<=n-1;i++)
{
int x,y,z;
cin>>x>>y>>z;
a[x].push_back({y,z});
a[y].push_back({x,z});
edge.push_back({x,y});
}
for(int i=1;i<=s;i++)
{
int x;
cin>>x;
str[x]=1;
}
dfs(e,0);
dfs2(e,0);
dfs3(e,0);
while(q--)
{
int u,v;
cin>>u>>v;
if(h[edge[u].fi]>h[edge[u].se]) swap(edge[u].fi,edge[u].se);
// cout<<h[edge[u].se]<<" "<<h[v]<<" "<<edge[u].se<<" "<<v<<endl;
if(h[edge[u].fi]>=h[v])
{
cout<<"escaped"<<endl;
continue;
}
int gap=-h[edge[u].se]+h[v];
// cout<<"type2";
int v2=v;
for(int i=0;i<=20;i++)
{
if(gap&(1<<i))
{
gap-=(1<<i);
v2=up[v2][i];
}
}
if(v2!=edge[u].se)
{
cout<<"escaped"<<endl;
continue;
}
gap=-h[edge[u].se]+h[v];
ll ans=MAX;
v2=v;
for(int i=0;i<=20;i++)
{
if(gap&(1<<i))
{
gap-=(1<<i);
ans=min(ans,cost[v]+mn[v2][i]);
v2=up[v2][i];
}
}
// cout<<f[v]<<" "<<cost[v]<<" "<<;
ans=min(ans,f[v]-cost[v]);
if(ans>1e15) cout<<"oo"<<endl;
else cout<<ans<<endl;
}
// cout<<mn[5][1]<<cost[3]<<" "<<cost[4]<<" "<<cost[5]<<" "<<f[5];
}
/*
*/
