#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll,ll> pii;
int n,m,q,st,p[100001][18],level[100001];
ll dis[100001],mmin[100001],near[100001]; //mmin[x]=near[x]-dis[x] -> x is the highest node in the path
ll val[100001][18];
bool shop[100001];
vector<pii> edge,adj[100001];
void dfs(int x, int par) {
near[x]=1e18;
if (shop[x]) near[x]=0;
for (auto s : adj[x]) {
if (s.first==par) continue;
dis[s.first]=dis[x]+s.second;
dfs(s.first,x);
near[x]=min(near[x],near[s.first]+s.second);
}
mmin[x]=near[x]-dis[x];
}
void dfs2(int x, int par) {
level[x]=level[par]+1;
p[x][0]=par;
val[x][0]=mmin[x];
for (int i=1; i<18; ++i) {
p[x][i]=p[p[x][i-1]][i-1];
val[x][i]=min(val[x][i-1],val[p[x][i-1]][i-1]);
}
for (auto s : adj[x]) {
if (s.first==par) continue;
dfs2(s.first,x);
}
}
pii lca(int x, int y) { //LCA,min
if (level[x]<level[y]) swap(x,y);
int dif=level[x]-level[y];
ll mi=LLONG_MAX;
for (int i=0; i<18; ++i) {
if (dif&(1<<i)) {
mi=min(mi,val[x][i]);
x=p[x][i];
}
}
if (x==y) return pii(x,min(mi,val[x][0]));
for (int i=17; i>=0; --i) {
if (p[x][i]!=p[y][i]) {
mi=min({mi,val[x][i],val[y][i]});
x=p[x][i];
y=p[y][i];
}
}
return pii(p[x][0],min({mi,val[x][1],val[y][1]}));
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>m>>q>>st;
for (int i=0; i<n-1; ++i) {
int a,b,w; cin>>a>>b>>w;
adj[a].push_back(pii(b,w));
adj[b].push_back(pii(a,w));
edge.push_back(pii(a,b));
}
for (int i=0; i<m; ++i) {
int s; cin>>s;
shop[s]=true;
}
dfs(st,st);
dfs2(st,st);
while (q--) {
int e,s; cin>>e>>s;
int u=edge[e-1].first, v=edge[e-1].second;
if (level[u]>level[v]) swap(u,v); //u-up, v-down
pii res=lca(s,v);
if (res.first!=v) cout<<"escaped\n";
else if (res.second>1e16) cout<<"oo\n";
else cout<<res.second+dis[s]<<"\n";
}
}
