#include <bits/stdc++.h>
using namespace std;
#define scd(t) scanf("%d", &t)
#define scld(t) scanf("%ld", &t)
#define sclld(t) scanf("%lld", &t)
#define scc(t) scanf("%c", &t)
#define scs(t) scanf("%s", t)
#define scf(t) scanf("%f", &t)
#define sclf(t) scanf("%lf", &t)
#define forr(i, j, k) for (int i = j; i < k; i++)
#define frange(i, j) forr(i, 0, j)
#define all(cont) cont.begin(), cont.end()
#define mp make_pair
#define pb push_back
#define f first
#define s second
typedef long int li;
typedef unsigned long int uli;
typedef long long int lli;
typedef unsigned long long int ulli;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<lli> vll;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vi> vvi;
typedef map<int, int> mpii;
typedef set<int> seti;
typedef multiset<int> mseti;
typedef long double ld;
void usaco()
{
freopen("input.in", "r", stdin);
// freopen("problem.out", "w", stdout);
}
vector<vii> graph;
vector<pair<pii, int>> edges;
vvi lift;
vector<vll> liftmi;
vi depth;
vll dp;
vll dist;
vb shop;
void dfs(int x, int par, int dt, lli d) {
if(shop[x]) dp[x] = 0;
depth[x] = dt;
dist[x] = d;
lift[0][x] = par;
for(auto p : graph[x]) {
if(p.f != par) {
dfs(p.f, x, dt+1, d+p.s);
dp[x] = min(dp[x], dp[p.f] + p.s);
}
}
}
int binlift(int x, int c) {
frange(i, 20) {
if(c & (1<<i)) x = lift[i][x];
}
return x;
}
lli binval(int x, int c) {
lli mi = 1e18;
frange(i, 20) {
if(c & (1<<i)) {
mi = min(mi, liftmi[i][x]);
x = lift[i][x];
// printf("%lld %d\n", mi, x);
}
}
// printf("%lld %d\n", dp[x] - dist[x], x);
return min(dp[x] - dist[x], mi);
}
int main() {
usaco();
int n, st, q, e;
scd(n);
scd(st);
scd(q);
scd(e);
graph = vector<vii>(n+1);
depth = vi(n+1, 1);
dp = vll(n+1, 1e18);
dist = vll(n+1, 1e18);
frange(i, n-1) {
int a, b, w;
scd(a);
scd(b);
scd(w);
edges.pb(mp(mp(a, b), w));
graph[a].pb(mp(b, w));
graph[b].pb(mp(a, w));
}
shop = vb(n+1);
frange(i, st) {
int a;
scd(a);
shop[a] = true;
}
lift = vvi(20, vi(n+1));
liftmi = vector<vll>(20, vll(n+1, 1e18));
dfs(e, 0, 0, 0);
forr(i, 1, n+1) {
liftmi[0][i] = dp[i] - dist[i];
}
forr(i, 1, 20) {
forr(j, 1, n+1) {
lift[i][j] = lift[i-1][lift[i-1][j]];
liftmi[i][j] = min(liftmi[i-1][j], liftmi[i-1][lift[i-1][j]]);
}
}
frange(i, q) {
int ed, r;
scd(ed);
scd(r);
ed--;
int a = edges[ed].f.f;
int b = edges[ed].f.s;
if(depth[a] > depth[b]) swap(a, b);
if(depth[r] >= depth[b] && binlift(r, depth[r]- depth[b]) == b) {
// printf("%lld ", binval(r, depth[r] - depth[b]));
lli mi = dist[r] + binval(r, depth[r] - depth[b]);
if(mi <= 1e16) {
printf("%lld\n", mi);
}
else {
printf("oo\n");
}
}
else {
printf("escaped\n");
}
}
// forr(i, 1, n+1) printf("%lld ", dp[i]);
// printf("\n");
// forr(i, 1, n+1) printf("%lld ", dist[i]);
}
