#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pb push_back
using namespace std;
const ll N=1e5+5;
const ll INF=1e18;
vector<pair<ll,ll>> g[N];
vector<pair<ll,ll>> roads;
ll tin[N], tout[N];
ll mi[N][20],d[N][20],pa[N][20];
ll cd[N];
ll S[N];
ll top,t=0;
void dfs(ll v, ll p, ll dpre){
cd[v]=INF;
if(S[v]) cd[v]=0;
tin[v]=t;
t++;
d[v][0]=dpre;
pa[v][0]=p;
mi[v][0]=cd[p]+dpre;
for(ll i=1; i<20; i++){
pa[v][i]=pa[pa[v][i-1]][i-1];
d[v][i]=d[v][i-1]+d[pa[v][i-1]][i-1];
mi[v][i]=min(mi[v][i-1],d[v][i-1]+mi[pa[v][i-1]][i-1]);
}
for(auto u : g[v]){
if(u.fi==p) continue;
dfs(u.fi,v,u.se);
cd[v]=min(cd[v],cd[u.fi]+u.se);
}
tout[v]=t;
t++;
}
ll virs(ll a, ll b){
return (tin[a]<tin[b] && tout[a]>tout[b]);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
ll n,s,q;
cin>>n>>s>>q>>top;
for(ll i=0; i<n-1; i++){
ll a,b,w;
cin>>a>>b>>w;
g[a].pb({b,w});
g[b].pb({a,w});
roads.pb({a,b});
}
for(ll i=0; i<s; i++){
ll a; cin>>a;
S[a]=1;
}
dfs(top,top,0);
for(ll i=0; i<q; i++){
ll ban,r;
cin>>ban>>r;
ll a=roads[ban-1].fi,b=roads[ban-1].se;
if(virs(b,a)) swap(b,a);
if(tin[a]<tin[r] && tout[a]>tout[r] && tout[b]>=tout[r] && tin[b]<=tin[r]){
ll atb=cd[r];
ll l=20;
while(l>0){
l--;
ll nr=pa[r][l];
if(virs(nr,b)) continue;
atb=min(atb,mi[r][l]);
r=nr;
}
if(atb==INF) cout<<"oo\n";
else cout<<atb<<'\n';
}
else cout<<"escaped\n";
}
return 0;
}
