#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb push_back
const int lg = 17 + 2, maxn = 1e5 + 4;
const ll inf = 1ll << 62, maxa = 1e15;
int n, s, q, e, low[maxn], anc[maxn][lg], cnt[maxn];
ll mn[maxn], d[maxn], cost[maxn][lg];
bitset<maxn> mark;
vector<array<int, 3>> g[maxn];
void dfs(int v, int par) {
if (v != e) {
anc[v][0] = par;
for (int i = 1; i < lg; ++i) {
int u = anc[v][i - 1];
if (u != -1) {
anc[v][i] = anc[u][i - 1];
}
}
}
if (mark[v]) {
mn[v] = d[v];
}
for (auto [u, w, ind] : g[v]) {
if (u != par) {
cnt[u] = cnt[v] + 1;
d[u] = d[v] + w;
low[ind] = u;
dfs(u, v);
mn[v] = min(mn[v], mn[u]);
}
}
}
void calc(int v, int par) {
cost[v][0] = mn[v] - (d[v] << 1);
for (int i = 1; i < lg; ++i) {
ll t = cost[v][i - 1];
int u = anc[v][i - 1];
if (u != -1) {
t = min(t, cost[u][i - 1]);
}
cost[v][i] = t;
}
for (auto [u, w, ind] : g[v]) {
if (u != par) {
calc(u, v);
}
}
}
int up(int v, ll dis) {
for (int i = 0; i < lg; ++i) {
if (((1 << i) & dis) && v != -1) {
v = anc[v][i];
}
}
return v;
}
ll ans(int v, ll dis) {
ll ret = inf;
for (int i = 0; i < lg; ++i) {
if (((1 << i) & dis) && v != -1) {
ret = min(ret, cost[v][i]);
v = anc[v][i];
}
}
return ret;
}
int main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n >> s >> q >> e;
for (int i = 0; i < n - 1; ++i) {
int v, u, w;
cin >> v >> u >> w;
--v, --u;
g[v].pb({u, w, i});
g[u].pb({v, w, i});
}
for (int i = 0; i < s; ++i) {
int v;
cin >> v;
--v;
mark[v] = 1;
}
for (int i = 0; i < n; ++i) {
mn[i] = inf;
for (int j = 0; j < lg; ++j) {
anc[i][j] = -1;
cost[i][j] = inf;
}
}
--e;
dfs(e, e);
calc(e, e);
for (int i = 0; i < q; ++i) {
int f, v;
cin >> f >> v;
--f, --v;
int u = low[f];
ll dis = cnt[v] - cnt[u];
if (dis < 0 || up(v, dis) != u) {
cout << "escaped\n";
}
else {
ll t = ans(v, dis + 1) + d[v];
if (t > maxa) {
cout << "oo\n";
}
else {
cout << t << '\n';
}
}
}
return 0;
}
