#include <bits/stdc++.h>
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;
const ld eps=1e-7;
const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod = 1000000007;
const int MAXN = 100010, LOG=20;
ll n, m, q, k, u, v, x, y, t, a, b, root;
int E[MAXN][3];
int stt[MAXN], fnt[MAXN], timer=1;
int par[MAXN], parid[MAXN];
ll seg[MAXN<<2], lazy[MAXN<<2];
ll ans[MAXN];
vector<int> G[MAXN];
vector<pii> Q[MAXN];
void add_lazy(int id, ll val){
seg[id]+=val;
lazy[id]+=val;
}
void shift(int id){
if (!lazy[id]) return ;
add_lazy(id<<1, lazy[id]);
add_lazy(id<<1 | 1, lazy[id]);
lazy[id]=0;
}
void Add(int id, int tl, int tr, int l, int r, ll val){
if (r<=tl || tr<=l) return ;
if (l<=tl && tr<=r){
add_lazy(id, val);
return ;
}
shift(id);
int mid=(tl+tr)>>1;
Add(id<<1, tl, mid, l, r, val);
Add(id<<1 | 1, mid, tr, l, r, val);
seg[id]=min(seg[id<<1], seg[id<<1 | 1]);
}
ll Get(int id, int tl, int tr, int l, int r){
if (r<=tl || tr<=l) return seg[0];
if (l<=tl && tr<=r) return seg[id];
shift(id);
int mid=(tl+tr)>>1;
return min(Get(id<<1, tl, mid, l, r), Get(id<<1 | 1, mid, tr, l, r));
}
void dfs1(int node){
stt[node]=timer++;
for (int v:G[node]) if (v!=par[node]){
par[v]=node;
dfs1(v);
}
fnt[node]=timer;
}
void dfs2(int node){
for (pii p:Q[node]) ans[p.second]=Get(1, 1, n+1, stt[p.first], fnt[p.first]);
for (int v:G[node]) if (v!=par[node]){
int id=parid[v];
Add(1, 1, n+1, 1, n+1, E[id][2]);
Add(1, 1, n+1, stt[v], fnt[v], -2*E[id][2]);
dfs2(v);
Add(1, 1, n+1, 1, n+1, -E[id][2]);
Add(1, 1, n+1, stt[v], fnt[v], 2*E[id][2]);
}
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
seg[0]=INF;
cin>>n>>m>>q>>root;
for (int i=1; i<n; i++){
cin>>E[i][0]>>E[i][1]>>E[i][2];
G[E[i][0]].pb(E[i][1]);
G[E[i][1]].pb(E[i][0]);
}
dfs1(root);
while (m--){
cin>>v;
Add(1, 1, n+1, stt[v], stt[v]+1, -INF);
}
Add(1, 1, n+1, 1, n+1, +INF);
for (int i=1; i<n; i++){
if (par[E[i][0]]!=E[i][1]) swap(E[i][0], E[i][1]);
parid[E[i][0]]=i;
Add(1, 1, n+1, stt[E[i][0]], fnt[E[i][0]], E[i][2]);
}
for (int i=1; i<=q; i++){
cin>>x>>v;
if (stt[E[x][0]]<=stt[v] && fnt[v]<=fnt[E[x][0]]) Q[v].pb({E[x][0], i});
else ans[i]=-1;
}
dfs2(root);
for (int i=1; i<=q; i++){
if (ans[i]<0) cout<<"escaped\n";
else if (ans[i]>=INF) cout<<"oo\n";
else cout<<ans[i]<<'\n';
}
return 0;
}
