// Born_To_Laugh - Hughie Do
#include <bits/stdc++.h>
#define alle(AC) AC.begin(), AC.end()
#define fi first
#define se second
using namespace std;
typedef long long ll;
[[maybe_unused]] const ll MOD = 998244353, INF = 3e18 + 7;
const int maxn = 1e5 + 10;
int n, q, s, e, id = 0;
vector<pair<int, int>> adj[maxn];
int isC[maxn];
int tin[maxn], tout[maxn];
ll binlift[maxn][20], qr[maxn][20];
ll dp[maxn], dep[maxn];
ll val[maxn];
pair<pair<int, int>, int> edge[maxn];
void dfs(int a, int par){
tin[a] = ++id;
if(isC[a]) dp[a] = 0;
else dp[a] = INF;
for(auto &elm: adj[a]){
if(elm.fi == par) continue;
dep[elm.fi] = dep[a] + elm.se;
dfs(elm.fi, a);
dp[a] = min(dp[a], dp[elm.fi] + elm.se);
}
tout[a] = id;
}
void dfsbl(int a, int par){
for(auto &elm: adj[a]){
int x = elm.fi, w = elm.se;
if(x == par) continue;
binlift[x][0] = a;
qr[x][0] = dp[a] - dep[a];
for(int i=1; i<20; ++i){
binlift[x][i] = binlift[binlift[x][i - 1]][i - 1];
qr[x][i] = min(qr[x][i - 1], qr[binlift[x][i - 1]][i - 1]);
}
dfsbl(x, a);
}
}
void solve(){
cin >> n >> s >> q >> e;
for(int i=1; i<n; ++i){
int a, b, c;cin >> a >> b >> c;
adj[a].push_back({b, c});
adj[b].push_back({a, c});
edge[i] = {{a, b}, c};
}
for(int i=1; i<=s; ++i){
int x;cin >> x;
isC[x] = 1;
}
dfs(e, -1);
dfsbl(e, -1);
while(q--){
int lon, r;cin >> lon >> r;
int a = edge[lon].fi.fi, b = edge[lon].fi.se;
if(dep[a] > dep[b]) swap(a, b);
if(tin[b] <= tin[r] && tin[r] <= tout[b]){
int x = r;
ll ans = dp[r];
for(int i=19; i>=0; --i){
if(dep[binlift[x][i]] >= dep[b]){
ans = min(ans, dep[r] + qr[x][i]);
x = binlift[x][i];
}
}
if(ans >= INF){
cout << "oo\n";
}
else cout << ans << '\n';
}
else{
cout << "escaped\n";
}
}
}
signed main(){
// freopen("inp.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
solve();
}
