#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 200005;
const int INF = 1LL << 60;
int n, s, q, e;
vector<pair<int,int>> adj[maxn];
pair<int,int> edges[maxn];
int dist[maxn];
int dpth[maxn];
int closest[maxn];
int shop[maxn];
int bl[maxn][20];
int bld[maxn][20];
int st[maxn], en[maxn], cur = 0;
void dfs(int nd, int par, int d) {
st[nd] = cur++;
dist[nd] = dist[par] + d;
dpth[nd] = dpth[par] + 1;
for (auto i : adj[nd])
if (i.first != par)
dfs(i.first, nd, i.second);
closest[nd] = (shop[nd] ? dist[nd] : INF);
for (auto i : adj[nd])
if (i.first != par && closest[i.first] != INF)
closest[nd] = min(closest[nd], closest[i.first]);
en[nd] = cur++;
}
void dfs_bl(int nd, int par) {
bl[nd][0] = par;
bld[nd][0] = (closest[nd] == INF ? INF : closest[nd] - 2 * dist[nd]);
for (int i = 1; i < 20; i++) bl[nd][i] = bl[bl[nd][i-1]][i-1];
for (int i = 1; i < 20; i++) bld[nd][i] = min(bld[nd][i-1], bld[bl[nd][i-1]][i-1]);
for (auto i : adj[nd])
if (i.first != par)
dfs_bl(i.first, nd);
}
signed main() {
cin >> n >> s >> q >> e; e--;
for (int i = 0; i < n-1; i++) {
int a, b, c; cin >> a >> b >> c; a--, b--;
adj[a].push_back({b, c});
adj[b].push_back({a, c});
edges[i] = make_pair(a, b);
}
for (int i = 0; i < s; i++) {
int a; cin >> a; a--;
shop[a] = 1;
}
dfs(e, e, 0);
dfs_bl(e, e);
for (int i = 0; i < n-1; i++)
if (dpth[edges[i].first] < dpth[edges[i].second])
swap(edges[i].first, edges[i].second);
for (int i = 0; i < q; i++) {
int a, b; cin >> a >> b; a--, b--;
// can escape?
if (!(st[edges[a].first] <= st[b] && en[b] <= en[edges[a].first])) {
cout << "escaped" << endl;
continue;
}
int cost = INF;
int nd = b;
for (int i = 19; i >= 0; i--)
if (((dpth[b] - dpth[edges[a].first]) >> i) & 1)
cost = min(cost, bld[nd][i]),
nd = bl[nd][i];
cost = min(cost, bld[nd][0]);
if (cost == INF) { cout << "oo" << endl; continue; }
cout << cost + dist[b] << endl;
continue;
}
return 0;
}
