using namespace std;
#include <bits/stdc++.h>
#define rep(i,a,b) for(int i = a; i < b; i++)
#define pb push_back
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<bool> vb;
int n, s, q;
int root;
vb shop;
vvi adj;
vvi roads;
vi parent, depth;
vector<ll> closestShopDown;
vector<vector<ll>> distanceUp, best;
vvi nodeUp;
map<pair<int,int>, ll> weight;
void dfs1(int x, int camefrom) {
parent[x] = camefrom;
if (shop[x]) closestShopDown[x] = 0;
for (auto v : adj[x]) if (v != camefrom) {
depth[v] = depth[x] + 1;
dfs1(v, x);
closestShopDown[x] = min(closestShopDown[x], closestShopDown[v] + weight[{x, v}]);
}
}
int up(int a, int x) {
rep(i,0,20) if (x & (1<<i)) a = nodeUp[a][i];
return a;
}
int lca(int a, int b) {
if (depth[a] > depth[b]) swap(a, b);
int change = depth[b] - depth[a];
a = up(a, change);
int low = 0, high = depth[a], mid;
while (high - low > 1) {
mid = (low + high) / 2;
if (up(b, mid) == up(a, mid)) high = mid;
else low = mid;
}
if (up(b, low) == up(a, low)) return up(a, low);
else return up(a, high);
}
bool samesubtree(int node, int sub) {
if (depth[node] < depth[sub]) return false;
int diff = (depth[node] - depth[sub]);
node = up(node, diff);
return (node == sub);
}
int main() {
cin >> n >> s >> q >> root;
root--;
adj.resize(n);
roads.resize(n-1);
rep(i,0,n-1) roads[i].resize(2);
rep(i,0,n-1) {
int a, b;
ll W;
cin >> a >> b >> W;
a--; b--;
roads[i][0] = a; roads[i][1] = b;
weight[{a, b}] = W;
weight[{b, a}] = W;
adj[a].pb(b); adj[b].pb(a);
}
shop.assign(n, false);
rep(i,0,s) {
int a; cin >> a; a--;
shop[a] = true;
}
depth.resize(n);
parent.assign(n, -1);
depth[root] = 0;
closestShopDown.assign(n, 1e18);
dfs1(root, -1);
const int lg = 20;
distanceUp.resize(n);
best.resize(n);
nodeUp.resize(n);
rep(i,0,n) {
distanceUp[i].assign(lg, 1e18);
best[i].assign(lg, 1e18);
nodeUp[i].assign(lg, -1);
}
rep(i,0,n) nodeUp[i][0] = parent[i];
rep(j,1,20) rep(i,0,n)
if (nodeUp[i][j - 1] != -1) nodeUp[i][j] = nodeUp[ nodeUp[i][j - 1] ][j - 1];
rep(i,0,n) {
if (i != root) distanceUp[i][0] = weight[{i, parent[i]}];
}
rep(j,1,lg) rep(i,0,n) {
if (nodeUp[i][j] == -1) continue;
// cout << i << " " << nodeUp[i][j] << endl;
// cout << nodeUp[i][j - 1] << endl;
distanceUp[i][j] = distanceUp[i][j - 1] + distanceUp[nodeUp[i][j - 1]][j - 1];
}
// cout << "here\n";
rep(i,0,n) best[i][0] = closestShopDown[i];
// rep(i,0,n) cout << best[i][0] << " "; cout << endl;
rep(j,1,lg) rep(i,0,n) {
best[i][j] = best[i][j-1];
if (nodeUp[i][j-1] == -1) continue;
best[i][j] = min(best[i][j - 1], distanceUp[i][j - 1] + best[nodeUp[i][j - 1]][j - 1]);
}
// rep(i,0,n) cout << best[i][1] << " "; cout << endl;
// rep(i,0,n) cout << best[i][2] << " "; cout << endl;
rep(Q,0,q) {
int I, node; cin >> I >> node; I--; node--;
int a = roads[I][0], b = roads[I][1];
if (depth[a] < depth[b]) swap(a, b);
if (!samesubtree(node, a)) {
cout << "escaped\n";
continue;
}
int diff = depth[node] - depth[a];
// cout << a << " " << depth[a] << ", " << node << " " << depth[node] << endl;
ll dist = 0;
ll ans = 1e18;
rep(i,0,lg) {
if (((1<<i) & diff) == 0) continue;
// cout << node << " " << i << endl;
ll nxt = dist + best[node][i+1];
// cout << nxt << endl;
ans = min(ans, nxt);
dist += distanceUp[node][i];
node = nodeUp[node][i];
}
if (ans < 1e18) cout << ans << endl;
else cout << "oo\n";
}
}
