//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define int long long
#define ll long long
#define fi first
#define se second
#define pb push_back
#define all(lmao) lmao.begin(), lmao.end()
using namespace std;
typedef pair<int,int> pii;
typedef tuple<int,int,int> tp;
const int N = 1e5 + 5;
const int oo = 1e16;
const int mod = 1e9 + 7;
int n, s, q, e, X[N], Y[N], W[N];
bool fl[N];
vector<pii> p[N], Q[N];
struct ST{
int T[N << 2], lz[N << 2];
void dolz(int i){
if(lz[i] == 0) return;
int x = lz[i];
lz[i] = 0;
T[i << 1] += x;
T[i << 1|1] += x;
lz[i << 1] += x;
lz[i << 1|1] += x;
}
void update(int i,int l,int r,int u,int v,int x){
if(l > v || r < u || l > r) return;
if(u <= l && r <= v){
T[i] += x;
lz[i] += x;
return;
}
dolz(i);
int mid = (l + r) >> 1;
update(i << 1, l, mid, u, v, x);
update(i << 1|1, mid + 1, r, u, v, x);
T[i] = min(T[i << 1], T[i << 1|1]);
}
int get(int i,int l,int r,int u,int v){
if(l > v || r < u ||l > r) return oo;
if(u <= l && r <= v) return T[i];
int mid = (l + r) >> 1;
dolz(i);
return min(get(i << 1, l, mid, u, v), get(i << 1|1, mid + 1, r, u, v));
}
} st;
namespace AC{
int in[N], demin, en[N], d[N], kq[N], f[N][22];
void pre(int u,int v){
in[u] = ++demin;
if(u == 1) for(int i = 0; i <= 20; i ++) f[u][i] = u;
else{
f[u][0] = v;
for(int i = 1; i <= 20; i ++) f[u][i] = f[f[u][i - 1]][i - 1];
}
for(auto [j, w] : p[u]){
if(j == v) continue;
d[j] = d[u] + w;
pre(j, u);
}
en[u] = demin;
}
bool kt(int u,int v){
return in[u] <= in[v] && in[v] <= en[u];
}
int cal(int x,int y){
int lca = x;
if(!kt(x, y)){
int h = x;
for(int i = 20; i >= 0; i --){
if(kt(f[h][i], y)) lca = f[h][i];
else h = f[h][i];
}
}
return d[x] + d[y] - 2 * d[lca];
}
void dfs(int u,int v){
for(auto [id, j] : Q[u]){
int x = X[j], y = Y[j];
if(in[x] > in[y]) swap(x, y);
if(kt(y, u)){
if(kt(y, e)) kq[id] = -1;
else kq[id] = st.get(1, 1, n, in[y], en[y]);
}else{
// cout << u << " " << id << " " << j << "h\n";
// for(int i = 1; i <= n; i ++) cout << i << " " << st.get(1, 1, n, in[i], in[i]) << "\n";
if(!kt(y, e)) kq[id] = -1;
else kq[id] = min(st.get(1, 1, n, 1, in[y] - 1), st.get(1, 1, n, en[y] + 1, n));
}
}
for(auto [j, w] : p[u]){
if(j == v) continue;
st.update(1, 1, n, 1, n, w);
st.update(1, 1, n, in[j], en[j], -2 * w);
dfs(j, u);
st.update(1, 1, n, 1, n, -w);
st.update(1, 1, n, in[j], en[j], 2 * w);
}
}
void solve(){
pre(1, 0);
for(int i = 1; i <= n; i ++){
if(fl[i]) st.update(1, 1, n, in[i], in[i], d[i]);
else st.update(1, 1, n, in[i], in[i], oo);
}
dfs(1, 0);
for(int i = 1; i <= q; i ++){
if(kq[i] == -1) cout << "escaped\n";
else if(kq[i] >= (int)1e14) cout << "oo\n";
else cout << kq[i] << "\n";
}
}
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define task "v"
if(fopen(task ".inp","r")){
freopen(task ".inp","r",stdin);
freopen(task ".out","w",stdout);
}
cin >> n >> s >> q >> e;
fl[e] = true;
for(int i = 1; i < n; i ++){
cin >> X[i] >> Y[i] >> W[i];
p[X[i]].pb({Y[i], W[i]});
p[Y[i]].pb({X[i], W[i]});
}
for(int i = 1; i <= s; i ++){
int x; cin >> x; fl[x] = true;
}
for(int i = 1; i <= q; i ++){
int j, r; cin >> j >> r;
Q[r].pb({i, j});
}
AC :: solve();
}
