#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll mod = 1e9 + 7;
const ll mod2 = 998244353;
ll gcd(ll a, ll b) {
return b ? gcd(b, a % b) : a;
}
ll pow(ll a, ll b) {
ll ans = 1;
while (b) {
if (b & 1) ans *= a;
b >>= 1;
a *= a;
}
return ans;
}
ll pow(ll a, ll b, ll c) {
ll ans = 1;
while (b) {
if (b & 1) ans = (ans * a) % c;
b >>= 1;
a = (a * a) % c;
}
return ans;
}
void check(bool b) {
if (b)
cout << "Yes\n";
else
cout << "No\n";
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
ll n,s,q,e;
cin>>n>>s>>q>>e;
vector<vector<pair<ll,ll>>> adj(n+1);
vector<pair<ll,ll>>edges;
for (int i = 0; i < n - 1; ++i) {
ll u,v,w;
cin>>u>>v>>w;
edges.push_back({u,v});
adj[u].push_back({v,w});
adj[v].push_back({u,w});
}
vector<ll>par(n+1),dp(n+1,1e18),par_dist(n+1),tin(n+1),tout(n+1);
for (int i = 0; i < s; ++i) {
ll x;
cin>>x;
dp[x]=0;
}
ll timer=0;
function<void(ll,ll)>dfs=[&](ll u,ll p){
tin[u]=++timer;
par[u]=p;
for(auto [v,w]:adj[u]){
if(v==p)continue;
par_dist[v]=w;
dp[u]=min(dp[u],dp[v]+w);
dfs(v,u);
}
tout[u]=++timer;
};
dfs(e,e);
ll l=log2(n)+1;
vector<vector<ll>>anc(n+1,vector<ll>(l)),min_anc(n+1,vector<ll>(l)),dist(n+1,vector<ll>(l));
for (int i = 1; i <= n; ++i) {
anc[i][0]=par[i];
dist[i][0]=par_dist[i];
min_anc[i][0]=min(par_dist[i]+dp[par[i]],dp[i]);
}
for (int j = 1; j < l; ++j) {
for (int i = 1; i <= n; ++i) {
anc[i][j]=anc[anc[i][j-1]][j-1];
dist[i][j]=dist[i][j-1]+dist[anc[i][j-1]][j-1];
min_anc[i][j]=min(min_anc[i][j-1],min_anc[anc[i][j-1]][j-1]+dist[i][j-1]);
}
}
function<bool(ll,ll)>is_ancestor=[&](ll u,ll v){
return tin[u]<=tin[v]&&tout[u]>=tout[v];
};
function<bool(ll,ll)>is_hard_ancestor=[&](ll u,ll v){
return tin[u]<tin[v]&&tout[u]>tout[v];
};
while (q--){
ll x,v;
cin>>x>>v;--x;
x=(is_ancestor(edges[x].first,edges[x].second)?edges[x].second:edges[x].first);
if (!is_ancestor(x,v)){
cout<<"escaped\n";
continue;
}
ll ans=dp[v],z=0;
for (int i = l-1; i >=0 ; --i) {
if (!is_hard_ancestor(anc[v][i],x)){
ans= min(ans,min_anc[v][i]+z);
z+=dist[v][i];
v=anc[v][i];
}
}
if (ans==1e18){
cout<<"oo\n";
} else
cout<<ans<<'\n';
}
return 0;
}
