#include <bits/stdc++.h>
#define task "BriantheCrab"
#define int long long
#define pii pair <int, int>
#define fi first
#define se second
#define szf sizeof
#define sz(s) (int)((s).size())
using namespace std;
template <class T> void mini (T &t, T f) {if (t > f) t = f;}
template <class T> void maxi (T &t, T f) {if (t < f) t = f;}
const int maxN = 1e5 + 5;
const int inf = 1e18 + 7;
const int mod = 1e9 + 7;
const int LOG = 21;
struct Ed {
int u, v, w;
};
int n, s, q, e;
int timer = 0;
Ed edge[maxN];
int par[maxN], sz[maxN], head[maxN], in[maxN];
int d[maxN], h[maxN];
bool spe[maxN];
int dp[maxN], st[maxN][LOG], up[maxN][LOG];
vector <pii> adj[maxN];
void dfs (int u, int p) {
sz[u] = 1;
in[u] = ++ timer;
for (auto [v, _] : adj[u]) {
if (v != p) {
par[v] = u;
dfs (v, u);
sz[u] += sz[v];
}
}
}
void HLD (int u, int p, int h) {
head[u] = h;
if (adj[u].size () == 1 && u != e) {
return;
}
int nxt = 0, curmax = 0;
for (auto [v, _] : adj[u]) {
if (v == p) {
continue;
}
if (sz[v] > curmax) {
curmax = sz[v];
nxt = v;
}
}
HLD (nxt, u, h);
for (auto [v, _] : adj[u]) {
if (v != nxt && v != p) {
HLD (v, u, v);
}
}
}
int LCA (int u, int v) {
while (head[u] != head[v]) {
if (sz[head[u]] < sz[head[v]]) {
u = par[head[u]];
}
else {
v = par[head[v]];
}
}
return ((sz[u] > sz[v]) ? u : v);
}
void cal (int u, int p) {
dp[u] = inf;
//cout << u << '\n';
if (spe[u]) {
//cout << "hi\n";
dp[u] = d[u];
}
for (auto [v, w] : adj[u]) {
if (v == p) {
continue;
}
h[v] = h[u] + 1;
d[v] = d[u] + w;
//cout << v << ' ' <<u << '\n';
cal (v, u);
mini (dp[u], dp[v]);
}
}
void solve () {
cin >> n >> s >> q >> e;
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 <= s; i ++) {
int x;
cin >> x;
spe[x] = 1;
}
dfs (e, e);
HLD (e, e, e);
cal (e, e);
//cout << LCA (5, 1) << '\n';
for (int i = 1; i <= n; i ++) {
if (dp[i] != inf) {
dp[i] -= 2 * d[i];
}
}
for (int i = 1; i <= n; i ++) {
st[i][0] = dp[par[i]];
up[i][0] = par[i];
}
for (int j = 1; j < LOG; j ++) {
for (int i = 1; i <= n; i ++) {
up[i][j] = up[up[i][j - 1]][j - 1];
st[i][j] = min (st[i][j - 1], st[up[i][j - 1]][j - 1]);
}
}
// for (int i = 1; i <= n; i ++) {
// cout << d[i] << '\n';
// }
while (q --) {
int I, R;
cin >> I >> R;
auto [u, v, w] = edge[I];
if (in[u] < in[v]) {
swap (u, v);
}
v = R;
//cout << u << ' ' << v << ' ' << LCA (u, v) << '\n';
if (LCA (u, v) == u && h[u] <= h[v]) {
if (spe[v] == true) {
cout << "0\n";
}
//cout << dp[u] << ' ' << dp[v] << '\n';
else if (dp[u] == inf) {
cout << "oo\n";
}
else {
int cur = h[v] - h[u];
//cout << u << ' ' << v << ' ' << d[v] << '\n';
int bestL = dp[v];
int bestR = d[v];
for (int i = 0; i < LOG; i ++) {
if ((cur >> i) & 1) {
mini (bestL, st[v][i]);
v = up[v][i];
//cout << v << ' ' << dp[v] << '\n';
}
}
if (bestL + bestR < 0) {
cout << "oo\n";
continue;
}
cout << bestL + bestR << '\n';
}
}
else {
cout << "escaped\n";
}
}
}
signed main () {
cin.tie (nullptr) -> sync_with_stdio (false);
if (fopen (task".inp", "r")) {
freopen (task".inp", "r", stdin);
freopen (task".out", "w", stdout);
}
int t = 1;
//cin >> t;
while (t --) {
solve ();
}
return 0;
}
// thfdgb
