#include <bits/stdc++.h>
using namespace std;
#define TASK "long"
#define fi first
#define se second
#define ll long long
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define GETBIT(mask, i) ((mask) >> (i) & 1)
#define MASK(i) ((1LL) << (i))
#define SZ(x) ((int)(x).size())
#define mp make_pair
#define CNTBIT(mask) __builtin_popcount(mask)
template<class X, class Y> bool maximize(X &x, Y y){ if (x < y) {x = y; return true;} return false;};
template<class X, class Y> bool minimize(X &x, Y y){ if (x > y) {x = y; return true;} return false;};
typedef pair<int, int> ii;
const int N = 1e5 + 5;
const long long INF = (long long)1e18 + 7;
const int mod = 1e9 + 7;
struct Fenwick {
int n;
vector<long long> v;
Fenwick(int _n = 0) {
n = _n;
v.assign(n + 2, 0);
}
void update(int x, int c) {
for(; x <= n; x += x & -x) v[x] += c;
}
long long get(int x) {
long long ans = 0;
for(; x > 0; x -= x & -x) ans += v[x];
return ans;
}
long long get(int l, int r) {
return (get(r) - get(l - 1));
}
} fw;
struct SegTree {
int n;
vector<long long> st, lz;
SegTree(int _n = 0) {
n = _n;
st.assign(4 * n + 5, INF);
lz.assign(4 * n + 5, 0);
}
void down(int id) {
long long &t = lz[id];
if (t == 0) return;
for(int i = (id<<1); i <= (id<<1|1); i++) {
st[i] += (st[i] == INF ? 0 : t);
lz[i] += t;
}
t = 0;
}
void update(int id, int l, int r, int u, int v, int c) {
if (u > r || v < l) return;
if (u <= l && r <= v) {
// if (c == 2) cerr << "L R : " << l << ' ' << r << endl;
st[id] += (st[id] == INF ? 0 : c);
lz[id] += c;
return;
}
down(id);
int mid = (l + r) >> 1;
update(id<<1, l, mid, u, v, c);
update(id<<1|1, mid + 1, r, u, v, c);
st[id] = min(st[id<<1], st[id<<1|1]);
}
void update(int l, int r, int c) {
// if (c == 2) cout << l << ' ' << r << endl;
if (c >= INF) return;
return update(1, 1, n, l, r, c);
}
void update1(int id, int l, int r, int p, long long c) {
if (l == r) {
st[id] = c;
return;
}
down(id);
int mid = (l + r) >> 1;
if (p <= mid) update1(id<<1, l, mid, p, c);
else update1(id<<1|1, mid + 1, r, p, c);
st[id] = min(st[id<<1], st[id<<1|1]);
}
void update1(int p, long long c) {
if (c >= INF) return;
return update1(1, 1, n, p, c);
}
long long get(int id, int l, int r, int u, int v) {
if (u > r || v < l) return INF;
if (u <= l && r <= v) return st[id];
down(id);
int mid = (l + r) >> 1;
return min(get(id<<1, l, mid, u, v), get(id<<1|1, mid + 1, r, u, v));
}
long long get(int l, int r) {
return get(1, 1, n, l, r);
}
} it;
int n, q, numShop, root;
int tin[N], tout[N], high[N], head[N], sz[N], par[N];
bool isShop[N];
pair<long long, int> f1[N], f2[N];
pair<int, int> e[N];
vector<pair<int, int>> adj[N], queries[N];
vector<int> shops;
long long ans[N];
void read() {
cin >> n >> numShop >> q >> root;
for(int i = 1; i < n; i++) {
int u, v, c; cin >> u >> v >> c;
adj[u].push_back({v, c});
adj[v].push_back({u, c});
e[i] = {u, v};
}
shops.resize(numShop);
for(auto&i : shops) {
cin >> i;
isShop[i] = 1;
}
}
int timer = 0;
void dfs(int u, int p) {
sz[u] = 1;
par[u] = p;
for(auto& i: adj[u]) {
int v = i.fi;
if (v == p) continue;
high[v] = high[u] + 1;
dfs(v, u);
sz[u] += sz[v];
}
}
bool isChild(int u, int p) {
return tin[u] >= tin[p] && tin[u] <= tout[p];
}
void hld(int u, int p, int top, int w) {
tin[u] = ++timer;
head[u] = top;
// cerr << u << ' ' << head[u] << endl;
// if (p != -1) weight.update(tin[u], w);
int bigC = -1, bigW = -1;
for(auto &i: adj[u]) {
int v = i.fi;
if (v == p) continue;
if (bigC == -1 || sz[bigC] < sz[v]) {
bigC = v;
bigW = i.se;
}
}
if (bigC == -1) {
tout[u] = timer;
return;
}
hld(bigC, u, top, bigW);
for(auto &i: adj[u]) {
int v = i.fi;
if (v == p || v == bigC) continue;
hld(v, u, v, i.se);
}
tout[u] = timer;
}
void update(int u, int v, int c) {
while(head[u] != head[v]) {
if (high[head[u]] < high[head[v]]) swap(u, v);
it.update(tin[head[u]], tin[u], c);
u = par[head[u]];
}
if (high[u] > high[v]) swap(u, v);
it.update(tin[u], tin[v], c);
}
long long get(int u, int v) {
// if (high[u] < high[v]) swap(u, v);
long long ans = INF;
// cerr << "DB: " << u << ' ' << v << endl;
while(head[u] != head[v]) {
if (high[head[u]] < high[head[v]]) swap(u, v);
// cerr << it.get(tin[head[u]], tin[u]) << endl;
ans = min(ans, it.get(tin[head[u]], tin[u]));
// ans += weight.get(tin[head[u]], tin[u]);
// cerr << head[u] << ' ' << u << endl;
u = par[head[u]];
}
if (high[u] > high[v]) swap(u, v);
ans = min(ans, it.get(tin[u], tin[v]));
// ans += weight.get(tin[u] + 1, tin[v]);
return ans;
}
long long calF(int u, int p) {
f1[u] = f2[u] = {INF, 0};
if (isShop[u]) f1[u] = {0, u};
for(auto &i: adj[u]) {
int v = i.fi, c = i.se;
if (v == p) continue;
long long val = calF(v, u) + c;
if (f1[u].fi > val) {
f2[u] = f1[u];
f1[u] = mp(val, v);
}
else {
if (minimize(f2[u].fi, val)) f2[u].se = v;
}
}
// cerr << u << ' ' << f1[u].fi << ' ' << f1[u].se << endl;
return f1[u].fi;
}
void calQuery(int u, int p) {
for(auto [v, id]: queries[u]) {
ans[id] = f1[u].fi;
// cerr << "ANS: " << u << ' ' << f1[u].fi << endl;
ans[id] = min(ans[id], get(v, u));
// cerr << id << ' ' << u << ' ' << v << endl;
}
for(auto [v, c]: adj[u]) {
if (v == p) continue;
if (f1[u].fi == 0) {
// cerr << u << endl;
it.update1(tin[u], 0);
// cerr << u << ' ' << v << ' ' << 0 << endl;
}
else {
if (v == f1[u].se) {
it.update1(tin[u], f2[u].fi);
// cerr << u << ' ' << v << ' ' << f2[u].fi << endl;
}
else {
it.update1(tin[u], f1[u].fi);
// cerr << u << ' ' << v << ' ' << f1[u].fi << endl;
}
}
// cerr << u << ' ' << v << ' ' << c << endl;
// if (v == 5) cerr << "ANS: " << it.get(tin[3], tout[3]) << endl;
// cerr << "SEQ: " << tin[root] << ' ' << tin[u] << ' ' << c << endl;
update(root, u, c);
calQuery(v, u);
update(root, u, -c);
// cerr << -c << endl;
}
}
void sub1() {
fw = Fenwick(n);
dfs(root, -1);
hld(root, -1, root, 0);
for(int shop: shops) fw.update(tin[shop], 1);
for(int i = 1; i <= q; i++) {
int road, node; cin >> road >> node;
int u = e[road].fi, v = e[road].se;
if (high[u] > high[v]) swap(u, v);
if (isChild(node, v)) {
if (fw.get(tin[v], tout[v]) == 0) {
// cout << "oo\n";
ans[i] = INF;
continue;
}
if (numShop == n) {
ans[i] = 0;
// cout << 0 << endl;
continue;
}
queries[node].push_back({v, i});
// long long ans = INF;
// for(int shop: shops) if (isChild(shop, v)) {
// ans = min(ans, get(shop, node));
// }
// cout << ans << endl;
}
else {
// cout << "escaped\n";
ans[i] = -1;
}
}
calF(root, -1);
// for(int i = 1; i <= n; i++) cout << f1[i].fi << ' ' << f1[i].se << ' ' << f2[i].fi << ' ' << f2[i].se << endl;
// cerr << f1[3].fi << ' ' << f1[3].se << endl;
it = SegTree(n);
calQuery(root, -1);
for(int i = 1; i <= q; i++) {
if (ans[i] == INF) cout << "oo";
else if (ans[i] == -1) cout << "escaped";
else cout << ans[i];
cout << endl;
}
}
void solve() {
sub1();
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen(TASK".inp", "r")) {
freopen(TASK".inp", "r", stdin);
freopen(TASK".out", "w", stdout);
}
int test = 1;
// cin >> test;
while(test--) {
read();
solve();
}
return 0;
}
