/// dwuy: _,\,,,_\,__,\,,_
#include <bits/stdc++.h>
#define fastIO ios_base::sync_with_stdio(false); cin.tie(NULL)
#define file(a) freopen(a".inp","r",stdin); freopen(a".out", "w",stdout)
#define fi first
#define se second
#define endl "\n"
#define len(s) int32_t(s.length())
#define MASK(k)(1LL<<(k))
#define TASK "test"
#define int long long
using namespace std;
typedef tuple<int, int, int> tpiii;
typedef pair<double, double> pdd;
typedef pair<int, int> pii;
typedef long long ll;
const long long OO = 1e18;
const int MOD = 1e9 + 7;
const int INF = 1e9;
const int MX = 100005;
int n, S, q, E;
int c[MX];
pii edges[MX];
vector<pii> G[MX];
bitset<MX> isS = 0;
void nhap(){
cin >> n >> S >> q >> E;
for(int i=1; i<n; i++){
int u, v, w;
cin >> u >> v >> w;
edges[i] = {u, v};
G[u].push_back({v, w});
G[v].push_back({u, w});
}
for(int i=1; i<=S; i++){
int u; cin >> u;
isS[u] = 1;
}
}
int dfsID = 0;
int h[MX];
int d[MX];
int num[MX];
int rnum[MX];
int clo[MX];
int dpDown[MX];
int p[MX][17];
int f[MX][17];
int mn[MX][17];
void dfs(int u){
h[u] = h[p[u][0]] + 1;
num[u] = ++dfsID;
rnum[num[u]] = u;
if(isS[u]) dpDown[u] = 0;
else dpDown[u] = OO;
pii best = {dpDown[u], 0};
pii _best = {OO, 0};
for(pii &tmp: G[u]){
int v, c; tie(v, c) = tmp;
if(v == p[u][0]) continue;
p[v][0] = u;
d[v] = d[u] + c;
dfs(v);
dpDown[u] = min(dpDown[u], dpDown[v] + c);
if(dpDown[v] + c <= best.fi){
_best = best;
best = {dpDown[v] + c, v};
}
else _best = min(_best, {dpDown[v]+c, v});
}
for(pii &tmp: G[u]){
int v, c; tie(v, c) = tmp;
if(v == p[u][0]) continue;
if(best.se == v) f[v][0] = d[u] - _best.fi;
else f[v][0] = d[u] - best.fi;
}
clo[u] = dfsID;
}
int LCA(int u, int v){
if(h[u] > h[v]) swap(u, v);
for(int t=h[v] - h[u]; t; t-=-t&t) v = p[v][__lg(-t&t)];
if(u == v) return u;
for(int i=16; i>=0; i--) if(p[v][i] != p[u][i]){
u = p[u][i];
v = p[v][i];
}
return p[u][0];
}
int getMin(int l, int r){
if(l>r) return OO;
int k = __lg(r-l+1);
return min(mn[l][k], mn[r-MASK(k)+1][k]);
}
void solve(){
dfs(1);
for(int j=1; j<=16; j++){
for(int i=1; i<=n; i++){
p[i][j] = p[p[i][j-1]][j-1];
f[i][j] = max(f[i][j-1], f[p[i][j-1]][j-1]);
}
}
for(int i=1; i<n; i++) if(h[edges[i].fi] > h[edges[i].se]){
swap(edges[i].fi, edges[i].se);
}
for(int i=1; i<=n; i++){
mn[i][0] = isS[i]? d[rnum[i]] : OO;
// cout << "rmq: " << i << ' ' << mn[i][0] << endl;
}
for(int j=1; j<=16; j++){
for(int i=1; i+MASK(j)-1<=n; i++){
mn[i][j] = min(mn[i][j-1], mn[i+MASK(j-1)][j-1]);
}
}
while(q--){
int i, u;
cin >> i >> u;
int v = edges[i].se;
int puv = LCA(u, v);
int pue = LCA(u, E);
if(!((LCA(u, v)==v || LCA(E, v)==v) && LCA(edges[i].fi, pue) == pue)){
cout << "escaped\n";
continue;
}
int res = OO;
if(puv == v){
res = dpDown[u];
int mx = -1e18;
int t = u;
for(int i=16; i>=0; i--) if(h[p[u][i]]>=h[puv]){
mx = max(mx, f[u][i]);
u = p[u][i];
}
res = min(res, d[t] - mx);
}
else if(puv == u){
res = min(getMin(num[u], num[v]-1), getMin(clo[v]+1, clo[u])) - d[u];
int mx = -1e18;
for(int i=16; i>=0; i--) if(p[u][i]!=0){
mx = max(mx, f[u][i]);
u = p[u][i];
}
res = min(res, d[puv] - mx);
}
else{
int t = u;
res = dpDown[u];
// cerr << " huhu: " << res << endl;
int mx = -1e18;
for(int i=16; i>=0; i--) if(h[p[u][i]]+1 < puv){
mx = max(mx, f[u][i]);
u = p[u][i];
}
res = min(res, d[t] - mx);
res = min(res, d[t] - d[puv] + min(getMin(num[puv], num[v]-1), getMin(clo[v]+1, clo[puv])));
u = puv;
mx = -1e18;
for(int i=16; i>=0; i--) if(p[u][i]!=0){
mx = max(mx, f[u][i]);
u = p[u][i];
}
res = min(res, h[t] - mx);
}
if(res > 1e17) cout << "oo\n";
else cout << res << endl;
}
}
int32_t main(){
fastIO;
//file(TASK);
nhap();
solve();
return 0;
}
