#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define dbg(x) cout << #x << '=' << x << '\n';
#define ll long long
#define sz size()
#define x first
#define y second
#define pi pair <int, int>
#define pii pair <pi, int>
#define vi vector <int>
const ll mod = 1000000007;
#define int ll
int n, s, q, e;
vector<int> d;
int f[100001], l[100001];
pi road[100001];
int dt[1001];
bitset<100001> sh;
vector <pi> g[100001];
void dfs(int p, int cur){
d.pb(cur);
for(pi i: g[cur]){
if(i.x!=p) dfs(cur, i.x);
}
d.pb(cur);
}
void bfs(int rip1, int rip2, int p, int cur){
for(pi i: g[cur]){
if(i.x!=p && (min(cur, i.x)!=rip1 || max(cur, i.x)!=rip2)){
dt[i.x]=dt[cur]+i.y;
bfs(rip1, rip2, cur, i.x);
}
}
}
int32_t main(){
ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
cin>>n>>s>>q>>e;
for(int i=1; i<=n-1; i++){
int x, y, z;
cin>>x>>y>>z;
road[i]={x, y};
g[x].pb({y, z});
g[y].pb({x, z});
}
for(int i=1; i<=s; i++){
int x;
cin>>x;
sh[x]=1;
}
dfs(0, e);
for(int i=0; i<d.size(); i++){
l[d[i]]=i+1;
if(!f[d[i]]) f[d[i]]=i+1;
}
if(s==n){
//for(int i=1; i<=n; i++){cout<<i<<" "<<f[i]<<" "<<l[i]<<endl;}
for(int i=1; i<=q; i++){
int rd, r;
cin>>rd>>r;
int x=road[rd].x, y=road[rd].y;
if(f[x]<=f[r] && l[x]>=l[r] && f[y]<=f[r] && l[y]>=l[r]) cout<<0<<"\n";
else cout<<"escaped\n";
}
return 0;
}
for(int i=1; i<=q; i++){
int rd, r;
cin>>rd>>r;
int x=road[rd].x, y=road[rd].y;
if(x>y) swap(x, y);
if(f[x]<=f[r] && l[x]>=l[r] && f[y]<=f[r] && l[y]>=l[r]){
for(int j=1; j<=n; j++) dt[j]=1e18;
dt[r]=0;
bfs(x, y, 0, r);
int ans=1e18;
for(int i=1; i<=n; i++){
if(sh[i]) ans=min(ans, dt[i]);
}
if(ans!=1e18) cout<<ans<<"\n";
else cout<<"oo\n";
}
else cout<<"escaped\n";
}
}
