#include <bits/stdc++.h>
#define ll long long
#define dl double
#define st first
#define nd second
#define II pair <int, int>
using namespace std;
const int N = 5 + 1e5;
const ll inf = 7 + 1e18;
struct Edge {
int u, v, w;
};
int node = 0, logn;
vector <int> in, ou, h;
vector <ll> f;
vector <Edge> e;
vector <vector <int>> adj, p;
void dfs(int u) {
in[u] = ++ node;
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (!in[v]) {
h[v] = h[u] + 1;
p[0][v] = u;
f[v] = f[u] + e[i].w;
dfs(v);
}
}
ou[u] = node;
}
int lca(int u, int v) {
if (h[u] < h[v])
swap(u, v);
for (int si = h[u] - h[v]; si > 0; si ^= si & -si) {
int i = __builtin_ctz(si & -si);
u = p[i][u];
}
if (u == v)
return u;
for (int i = logn - 1; i >= 0; i --)
if (p[i][u] != p[i][v]) {
u = p[i][u];
v = p[i][v];
}
return p[0][u];
}
ll dis(int u, int v) {
return f[u] + f[v] - f[lca(u, v)] * 2;
}
vector <int> siz, pre;
void dfs(int u, int par) {
siz[u] = 1;
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (v != par && pre[v] < 0) {
dfs(v, u);
siz[u] += siz[v];
}
}
}
int centroid(int u, int par) {
for (int i : adj[u]) {
int v = e[i].u + e[i].v - u;
if (pre[v] < 0 && v != par && siz[v] * 2 > siz[u])
return centroid(v, u);
}
return u;
}
void build(int u, int par) {
dfs(u, par);
int c = centroid(u, par);
pre[c] = par;
for (int i : adj[c]) {
int v = e[i].u + e[i].v - c;
if (pre[v] < 0)
build(v, c);
}
}
vector <int> lg;
bool cmp(int u, int v) {
return in[u] < in[v];
}
struct Tree {
vector <ll> a;
vector <vector <ll>> mi;
void build(int root) {
int n = a.size();
sort(a.begin(), a.end(), cmp);
mi.assign(logn, vector <ll> (n, 0));
for (int i = 0; i < n; i ++)
mi[0][i] = dis(a[i], root);
for (int i = 1; i < logn; i ++)
for (int u = 0; u < n; u ++)
if (u + (1 << i) - 1 < n)
mi[i][u] = min(mi[i - 1][u], mi[i - 1][u + (1 << (i - 1))]);
}
ll get_min(int l, int r) {
if (l > r)
return inf;
int bit = lg[r - l + 1];
return min(mi[bit][l], mi[bit][r - (1 << bit) + 1]);
}
ll get_ans(int l, int r, int type) {
if (a.empty())
return inf;
int n = a.size(), lo = 0, hi = n - 1;
while (lo < hi) {
int mid = (lo + hi) / 2;
if (in[a[mid]] >= l)
hi = mid;
else
lo = mid + 1;
}
if (type) {
if (l <= in[a[lo]] && in[a[lo]] <= r) {
int L = lo;
hi = n - 1;
while (lo < hi) {
int mid = (lo + hi + 1) / 2;
if (in[a[mid]] <= r)
lo = mid;
else
hi = mid - 1;
}
return get_min(L, lo);
}
return inf;
}
if (l <= in[a[lo]] && in[a[lo]] <= r) {
int L = lo;
hi = n - 1;
while (lo < hi) {
int mid = (lo + hi + 1) / 2;
if (in[a[mid]] <= r)
lo = mid;
else
hi = mid - 1;
}
return min(get_min(1, L - 1), get_min(lo + 1, n - 1));
}
return get_min(0, n - 1);
}
};
vector <Tree> T;
void update(int u) {
int v = u;
while (v > 0) {
T[v].a.push_back(u);
v = pre[v];
}
}
int main() {
#define TASKNAME ""
ios_base :: sync_with_stdio (0);
cin.tie (0);
if ( fopen( TASKNAME".inp", "r" ) ) {
freopen( TASKNAME".inp", "r", stdin );
freopen( TASKNAME".out", "w", stdout );
}
int n, s, q, root;
cin >> n >> s >> q >> root;
e.resize(n);
adj.resize(n + 1);
for (int i = 1; i < n; i ++) {
cin >> e[i].u >> e[i].v >> e[i].w;
adj[e[i].u].push_back(i);
adj[e[i].v].push_back(i);
}
vector <int> a(n + 1, 0);
for (int i = 1; i <= s; i ++) {
int u;
cin >> u;
a[u] = 1;
}
for (logn = 1; (1 << logn) <= n; logn ++);
p.assign(logn, vector <int> (n + 1, 0));
in.assign(n + 1, 0);
ou.assign(n + 1, 0);
h.assign(n + 1, 0);
f.assign(n + 1, 0);
h[1] = 1;
dfs(1);
for (int i = 1; i < logn; i ++)
for (int u = 1; u <= n; u ++)
p[i][u] = p[i - 1][p[i - 1][u]];
for (int i = 1; i < n; i ++)
if (in[e[i].u] > in[e[i].v])
swap(e[i].u, e[i].v);
if (s == n) {
while (q --) {
int id, u;
cin >> id >> u;
int l = in[e[id].v], r = ou[e[id].v], check = (l <= in[u] && in[u] <= r), v = u,
check1 = (l <= in[root] && in[root] <= r);
if (check == check1) {
cout << "escaped\n";
continue;
}
cout << "0\n";
}
return 0;
}
siz.assign(n + 1, 0);
pre.assign(n + 1, -1);
build(1, 0);
lg.assign(n + 1, 0);
for (int i = 2; i <= n; i ++)
lg[i] = lg[i >> 1] + 1;
T.resize(n + 1);
for (int i = 1; i <= n; i ++)
if (a[i])
update(i);
for (int i = 1; i <= n; i ++)
T[i].build(i);
while (q --) {
int id, u;
cin >> id >> u;
int l = in[e[id].v], r = ou[e[id].v], check = (l <= in[u] && in[u] <= r), v = u,
check1 = (l <= in[root] && in[root] <= r);
if (check == check1) {
cout << "escaped\n";
continue;
}
if (a[u]) {
cout << "0\n";
continue;
}
ll mi = inf;
while (v > 0) {
ll val = T[v].get_ans(l, r, check);
if (val < inf)
mi = min(mi, dis(u, v) + val);
v = pre[v];
}
if (mi < inf)
cout << mi << '\n';
else
cout << "oo\n";
}
return 0;
}
