// #pragma GCC optimize("Ofast")
// #include <bits/stdc++.h>
// using namespace std;
// #define int long long
// const int maxn = 100000;
// const int INF = 2000000000;
// int n, s, q, e; // nodes, numshops, numqueries, valleynode
// vector<pair<int,int>> adj[maxn];
// pair<int,int> edges[maxn];
// int shop[maxn]; // is shop?
// int closest[maxn]; // closest shop in subtree
// int dist[maxn]; // distance to root, set
// int dpth[maxn]; // depth from root, set
// int bl[maxn][20]; // set
// int bld[maxn][20]; // array[nd] = - 2 * dist[nd] + min(dist[shop]) for shop in subtree[dist]
// void dfs(int nd, int par, int pardist, int d) {
// // set depth
// dpth[nd] = d;
// // set binary lifting
// bl[nd][0] = par;
// for (int i = 1; i < 20; i++) bl[nd][i] = bl[bl[nd][i-1]][i-1];
// // recurse dfs, set distance from root
// for (auto i : adj[nd])
// if (i.first != par) {
// dist[i.first] = dist[nd] + i.second;
// dfs(i.first, nd, i.second, d+1);
// }
// // init closest shop in subtree
// closest[nd] = shop[nd] ? 0 : INF;
// for (auto i : adj[nd])
// if (i.first != par)
// closest[nd] = min(closest[nd], i.second + closest[i.first]);
// return;
// }
// void dfs_bld(int nd) {
// if (closest[nd] == INF) bld[nd][0] = INF;
// else bld[nd][0] = -dist[nd] + closest[nd];
// 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 != bl[nd][0])
// dfs_bld(i.first);
// }
// inline int jmp(int nd, int k) {
// for (int i = 19; i >= 0; i--) if ((k >> i) & 1) nd = bl[nd][i];
// return nd;
// }
// inline bool on_path(int nd, int nd2) {
// // checking if nd2 is on nd's path to root
// return (dpth[nd] >= dpth[nd2] && jmp(nd, dpth[nd] - dpth[nd2]) == nd2);
// }
// void solve() {
// cin >> n >> s >> q >> e; e--;
// for (int i = 0; i < n-1; i++) {
// int c; cin >> edges[i].first >> edges[i].second >> c;
// edges[i].first--, edges[i].second--;
// adj[edges[i].first].push_back({edges[i].second, c});
// adj[edges[i].second].push_back({edges[i].first, c});
// }
// for (int i = 0; i < s; i++) { int a; cin >> a; a--; shop[a] = 1; }
// dfs(e, e, 0, 0);
// dfs_bld(e);
// for (int i = 0; i < q; i++) {
// // a is a removed, b is b to find
// int a, b; cin >> a >> b; a--, b--;
// if (dpth[edges[a].first] < dpth[edges[a].second])
// swap(edges[a].first, edges[a].second);
// // check if escape possible
// if (!on_path(b, edges[a].first)) {
// cout << "escaped" << endl;
// continue;
// }
// // not possible, so search
// int val = INF;
// int B = b;
// for (int i = 19; i >= 0; i--)
// if (((dpth[edges[a].first] - dpth[b] + 1) >> i) & 1)
// val = min(val, bld[b][i]),
// b = bl[b][i];
// if (val == INF) {
// cout << "oo" << endl;
// continue;
// }
// cout << val + dist[B] << endl;
// continue;
// }
// }
// signed main() {
// cin.tie(nullptr) -> ios::sync_with_stdio(false);
// // freopen("main.in", "r", stdin);
// int t;
// // cin >> t;
// t=1;
// while(t--) solve();
// return 0;
// }
#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 100000;
const int INF = 1e18;
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 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;
closest[nd] = (closest[nd] ? 0 : INF);
for (auto i : adj[nd])
if (i.first != par)
dfs(i.first, nd, i.second);
for (auto i : adj[nd])
if (i.first != par && closest[i.first] != INF)
closest[nd] = min(closest[nd], i.second + 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] - 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() {
freopen("main.in", "r", stdin);
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(b, c);
}
for (int i = 0; i < s; i++) {
int a; cin >> a; a--;
closest[a] = 1;
}
dfs(e, e, 0);
dfs_bl(e, e);
for (int i = 0; i < q; i++) {
int a, b; cin >> a >> b; a--, b--;
if (dpth[edges[a].first] < dpth[edges[a].second]) swap(edges[a].first, edges[a].second);
// 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] + 1) >> i) & 1)
cost = min(cost, bld[nd][i]),
nd = bl[nd][i];
if (cost == INF) { cout << "oo" << endl; continue; }
cout << cost + dist[b] << endl;
continue;
}
return 0;
}
