#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
struct seg{
vector<ll> val, laz;
int n;
seg(int _n = 0){
n = _n;
val.resize(4 * n + 3, 0);
laz.resize(4 * n + 3, 0);
}
void push(int i){
ll t = laz[i];
if(t == 0) return;
laz[i] = 0;
laz[i * 2] += t;
laz[i * 2 + 1] += t;
val[i * 2] += t;
val[i * 2 + 1] += t;
}
void upd(int i, int l, int r, int u, int v, ll c){
if(r < u || v < l) return;
if(u <= l && r <= v){
laz[i] += c;
val[i] += c;
return;
}
push(i);
int m = (l + r) >> 1;
upd(i * 2, l, m, u, v, c);
upd(i * 2 + 1, m + 1, r, u, v, c);
val[i] = min(val[i * 2], val[i * 2 + 1]);
}
ll get(int i, int l, int r, int u, int v){
if(r < u || v < l) return oo;
if(u <= l && r <= v) return val[i];
push(i);
int m = (l + r) >> 1;
return min(get(i * 2, l, m, u, v), get(i * 2 + 1, m + 1, r, u, v));
}
} it;
const int maxN = 1e5 + 10;
int N, M, Q, S;
vector<pair<int, int>> adj[maxN];
array<int, 3> edges[maxN];
int timer, nChain = 1;
int nChild[maxN], chain[maxN], topNode[maxN], par[maxN], in[maxN], out[maxN];
ll dist[maxN], ans[maxN];
vector<pair<int, int>> queries[maxN];
void countChild(int u, int p = -1){
par[u] = p;
nChild[u] = 1;
for(auto o: adj[u]){
int v = o.fi;
int id = o.se;
if(v == p) continue;
countChild(v, u);
nChild[u] += nChild[v];
if(edges[id][0] == v) swap(edges[id][0], edges[id][1]);
}
}
void hld(int u){
if(topNode[nChain] == 0) topNode[nChain] = u;
chain[u] = nChain;
in[u] = ++timer;
int heavyNode = -1;
for(auto o: adj[u]){
int v = o.fi;
if(v == par[u]) continue;
if(heavyNode == -1 || nChild[heavyNode] < nChild[v]){
heavyNode = v;
}
}
if(heavyNode != -1){
hld(heavyNode);
}
for(auto o: adj[u]){
int v = o.fi;
if(v == par[u] || v == heavyNode) continue;
nChain++;
hld(v);
}
out[u] = timer;
}
void update(int a, int u, ll c){
while(true){
if(chain[u] == chain[a]){
it.upd(1, 1, N, in[a], in[u], c);
break;
}
int p = topNode[chain[u]];
it.upd(1, 1, N, in[p], in[u], c);
u = par[p];
}
}
ll query(int a, int u){
ll ans = oo;
while(true){
if(chain[u] == chain[a]){
minimize(ans, it.get(1, 1, N, in[a], in[u]));
break;
}
int p = topNode[chain[u]];
minimize(ans, it.get(1, 1, N, in[p], in[u]));
u = par[p];
}
return ans;
}
void calc(int u){
for(auto o: queries[u]){
int x = o.fi, id = o.se;
// cout << u << ' ' << x << ' ' << o.se << '\n';
if(!(in[x] <= in[u] && out[u] <= out[x])){
ans[id] = -1;
continue;
}
else{
ans[id] = query(x, u);
}
}
for(auto o: adj[u]){
int v = o.fi;
ll c = edges[o.se][2];
if(v == par[u]) continue;
update(S, u, c);
calc(v);
update(S, u, -c);
}
}
void dfs(int u, int p = -1){
for(auto o: adj[u]){
int v = o.fi;
ll c = edges[o.se][2];
if(v == p) continue;
dfs(v, u);
minimize(dist[u], dist[v] + c);
}
}
void solve(){
cin >> N >> M >> Q >> S;
for(int i = 1; i < N; i++){
int u, v, c; cin >> u >> v >> c;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
edges[i] = {u, v, c};
}
memset(dist, 0x3f, sizeof dist);
for(int i = 1; i <= M; i++){
int x; cin >> x;
dist[x] = 0;
}
countChild(S);
hld(S);
dfs(S);
for(int i = 1; i <= Q; i++){
int x, y; cin >> x >> y;
x = edges[x][1];
queries[y].push_back({x, i});
}
it = seg(N);
// for(int i = 1; i < N; i++){
// cout << edges[i][0] << ' ' << edges[i][1] << '\n';
// }
for(int i = 1; i <= N; i++){
it.upd(1, 1, N, in[i], in[i], dist[i]);
}
calc(S);
for(int i = 1; i <= Q; i++){
if(ans[i] == -1){
cout << "escaped\n";
}
else if(ans[i] >= oo){
cout << "oo\n";
}
else{
cout << ans[i] << '\n';
}
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("capsomayman.inp","r",stdin);
// freopen("capsomayman.out","w",stdout);
int t = 1;
// cin >> t;
while(t--){
solve();
}
return 0;
}
