#include<bits/stdc++.h>
using namespace std;
vector<vector<pair<long long, long long> > > adj;
vector<pair<pair<long long, long long>, long long> > edges;
vector<bool> store;
vector<long long> nearest;
vector<long long> dist;
vector<long long> level;
vector<vector<long long> > dp;
void dfs(long long u, long long p){
for(pair<long long, long long> x : adj[u]){
long long v = x.first;
if(v != p){
dp[v][0] = u;
dist[v] = dist[u] + x.second;
level[v] = level[u] + 1;
dfs(v, u);
nearest[u] = min(nearest[u], nearest[v] + x.second);
}
}
if(store[u]){
nearest[u] = 0;
}
}
long long binJump(long long u, long long val){
for(long long j = 0; j < 21; j++){
if(val & (1 << j)){
u = dp[u][j];
}
}
return u;
}
long long lca(long long a, long long b){
if(level[a] > level[b]){
swap(a, b);
}
b = binJump(b, level[b] - level[a]);
long long low = 0;
long long high = (1 << 20);
long long res = -1;
while(low <= high){
long long mid = (low + high)/2;
if(binJump(b, mid) == binJump(a, mid)){
res = mid;
high = mid - 1;
}
else{
low = mid + 1;
}
}
return binJump(b, res);
}
int main(){
long long n, s, q, e;
cin >> n >> s >> q >> e;
adj.resize(1 + n);
edges.resize(n);
store.resize(1 + n);
nearest.resize(1 + n, 1e18);
dist.resize(1 + n);
dp.resize(1 + n, vector<long long>(21, 0));
level.resize(1 + n);
for(long long i = 1; i < n; i++){
long long a, b, w;
cin >> a >> b >> w;
adj[a].push_back(make_pair(b, w));
adj[b].push_back(make_pair(a, w));
edges[i] = make_pair(make_pair(a, b), w);
}
for(long long i = 0; i < s; i++){
long long x;
cin >> x;
store[x] = true;
}
dfs(e, 0);
for(long long i = 1; i <= n; i++){
for(long long j = 1; j < 21; j++){
dp[i][j] = dp[dp[i][j - 1]][j - 1];
}
}
while(q--){
long long i, r;
cin >> i >> r;
long long u = edges[i].first.first;
long long v = edges[i].first.second;
if(dp[v][0] == u){
swap(u, v);
}
if(lca(u, r) == u){
if(nearest[u] == 1e18){
cout << "oo\n";
}
else{
if(s == n){
cout << 0 << "\n";
}
else{
long long ans = 1e18;
for(long long i = 1; i <= n; i++){
if(lca(u, i) == u && store[i]){
ans = min(ans, dist[r] + dist[i] - 2 * dist[lca(r, i)]);
// cout << u << " " << r << " " << i << " " << dist[r] + dist[i] - 2 * dist[lca(r, i)] << "\n";
}
}
cout << ans << "\n";
}
}
}
else{
cout << "escaped\n";
}
}
}
