//#pragma GCC optimization ("O3")
//#pragma GCC target ("avx2")
#pragma GCC optimization ("unroll-loops")
#pragma GCC optimize ("Ofast")
#pragma GCC target ("avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
#define all(s) s.begin(), s.end()
#define ok puts("ok")
#define ll long long
#define pb push_back
#define mk make_pair
#define fr first
#define sc second
#define vi vector < int >
#define pl pair < ll, ll >
#define pi pair < int, int >
#define pii pair < ll, pi >
#define next next123
#define left left123
const int N = 1e5 + 7;
const ll INF = 1e15 + 7;
ll d[N], ans[N], t[4 * N], lz[4 * N];
int h[N], tin[N], tout[N], tim;
int n, s, q, rt;
vector < pair < int, ll > > g[N];
vector < pi > ev[N];
struct edge{
int a, b;
ll w;
}e[N];
void push (int v, int l, int r){
if (l != r){
lz[v + v] += lz[v];
lz[v + v + 1] += lz[v];
}
t[v] += lz[v];
lz[v] = 0;
}
void upd (int v, int l, int r, int ql, int qr, ll val){
push(v, l, r);
if (ql <= l && r <= qr){
lz[v] = val;
push(v, l, r);
return;
}
if (r < ql || qr < l)
return;
int mid = (l + r) >> 1;
upd(v + v, l, mid, ql, qr, val);
upd(v + v + 1, mid + 1, r, ql, qr, val);
t[v] = min(t[v + v], t[v + v + 1]);
}
ll get (int v, int l, int r, int ql, int qr){
push(v, l, r);
if (ql <= l && r <= qr)
return t[v];
if (r < ql || qr < l)
return INF;
int mid = (l + r) >> 1;
return min(get(v + v, l, mid, ql, qr), get(v + v + 1, mid + 1, r, ql, qr));
}
void calc (int v, int p = 0){
h[v] = h[p] + 1;
tin[v] = ++tim;
for (auto to : g[v]){
if (to.fr != p){
calc(to.fr, v);
d[v] = min(d[v], d[to.fr] + to.sc);
}
}
tout[v] = tim;
}
bool check (int v, int u){
return tin[v] <= tin[u] && tout[u] <= tout[v];
}
void dfs (int v, int p = 0){
upd(1, 1, n, h[v], h[v], d[v]);
for (auto to : g[v]){
if (to.fr != p){
upd(1, 1, n, 1, h[v], to.sc);
dfs(to.fr, v);
upd(1, 1, n, 1, h[v], -to.sc);
}
}
for (pi it : ev[v])
ans[it.sc] = get(1, 1, n, h[it.fr], h[v]);
upd(1, 1, n, h[v], h[v], -d[v]);
}
main(){
cin >> n >> s >> q >> rt;
for (int i = 1; i < n; i++){
scanf("%d%d%lld", &e[i].a, &e[i].b, &e[i].w);
g[e[i].a].pb(mk(e[i].b, e[i].w));
g[e[i].b].pb(mk(e[i].a, e[i].w));
d[i] = INF;
}
d[n] = INF;
for (int i = 1; i <= s; i++){
int v;
scanf("%d", &v);
d[v] = 0;
}
calc(rt);
for (int i = 1; i <= q; i++){
int v, b, c;
scanf("%d%d", &v, &b);
c = e[v].a;
if (h[e[v].a] < h[e[v].b])
c = e[v].b;
if (check(c, b))
ev[b].pb(mk(c, i));
else
ans[i] = -1;
}
dfs(rt);
for (int i = 1; i <= q; i++){
if (ans[i] == -1)
puts("escaped");
else if (ans[i] >= INF)
puts("oo");
else
printf("%lld\n", ans[i]);
}
}
