#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, weight;
int n, q, numShop, root;
int tin[N], tout[N], high[N], head[N], sz[N], par[N];
pair<int, int> e[N];
vector<pair<int, int>> adj[N];
vector<int> shops;
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;
}
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;
}
long long get(int u, int v) {
// if (high[u] < high[v]) swap(u, v);
long long ans = 0;
// cerr << "DB: " << u << ' ' << v << endl;
while(head[u] != head[v]) {
if (high[head[u]] < high[head[v]]) swap(u, v);
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 += weight.get(tin[u] + 1, tin[v]);
return ans;
}
void sub1() {
fw = Fenwick(n);
weight = Fenwick(n);
dfs(root, -1);
hld(root, -1, root, 0);
for(int shop: shops) fw.update(tin[shop], 1);
while(q--) {
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";
continue;
}
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";
}
}
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;
}
