#include <bits/stdc++.h>
using namespace std;
const int LOG = 17;
int n,q,numshop,root;
int shop[100009];
vector <pair <int,int>> adj[100009];
struct {
int u,v,w;
} edge[100009];
int h[100009],up[100009][LOG + 1];
long long depth[100009];
void dfs(int node,int par) {
for (auto x : adj[node]) if (x.first != par) {
int ver = x.first,w = x.second;
h[ver] = h[node] + 1;
depth[ver] = depth[node] + w;
up[ver][0] = node;
for (int i = 1;i <= LOG;i++) up[ver][i] = up[up[ver][i - 1]][i - 1];
dfs(ver,node);
}
}
int raise(int node,int diff) {
for (int i = LOG;i >= 0;i--) if (diff >> i & 1) node = up[node][i];
return node;
}
namespace sub123 {
bool check() {
return 1ll*n*q <= 1000000 || numshop == n;
}
int lca(int u,int v) {
if (h[u] < h[v]) swap(u,v);
u = raise(u,h[u] - h[v]);
if (u == v) return u;
for (int i = LOG;i >= 0;i--) if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
return up[u][0];
}
bool _has(int child,int anc,int x,int y) {
return lca(child,y) == y && h[x] >= h[anc];
}
bool has(int u,int v,int x,int y) {
int d = lca(u,v);
return _has(u,d,x,y) || _has(v,d,x,y);
}
void solve() {
while (q--) {
int vertice,_;cin >> _ >> vertice;
int u = edge[_].u,v = edge[_].v;
//check escape
if (!has(vertice,root,u,v)) {
cout << "escaped\n";
continue;
}
//check shop
if (numshop == n) {
cout << 0 << '\n';
continue;
}
long long ret = 1e18;
for (int i = 1;i <= numshop;i++) if (!has(vertice,shop[i],u,v)) {
ret = min(ret,depth[vertice] + depth[shop[i]] - 2*depth[lca(vertice,shop[i])]);
}
if (ret == 1e18) cout << "oo\n";
else cout << ret << '\n';
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr);
// freopen(".inp","r",stdin);
// freopen(".out","w",stdout);
cin >> n >> numshop >> q >> root;
for (int i = 1;i < n;i++) {
int u,v,w;cin >> u >> v >> w;
adj[u].push_back({v,w});
adj[v].push_back({u,w});
edge[i] = {u,v,w};
}
for (int i = 1;i <= numshop;i++) {
cin >> shop[i];
}
dfs(root,-1);
for (int i = 1;i < n;i++) if (h[edge[i].u] > h[edge[i].v]) swap(edge[i].u,edge[i].v);
if (sub123::check()) {
sub123::solve();
return 0;
}
}
