#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define int long long
using namespace std;
const int mod = 1e9+7;
const ll inf = 1e18;
const int N = 2e5+5;
int n,s,q,e, a[N], u[N], v[N], w[N];
set<pair<int,int>>g[N];
void solve() {
cin >> n >> s >> q >> e;
for(int i = 1;i<n;i++) {
cin >> u[i] >> v[i] >> w[i];
g[u[i]].insert({v[i],w[i]});
g[v[i]].insert({u[i],w[i]});
}
for(int i = 1;i<=s;i++) {
cin >> a[i];
}
while(q--){
int i,r;
cin >> i >> r;
int uu = u[i], vv = v[i], ww = w[i];
g[uu].erase({vv,ww});
g[vv].erase({uu,ww});
vector<int>dist(n+1,inf);
dist[r] = 0;
set<pair<int,int>>st;
st.insert({0,r});
while(st.size()) {
auto [dv,ver] = *st.begin();
st.erase(st.begin());
for(auto [to,weight]:g[ver]) {
if(dist[to]>dist[ver]+weight) {
st.erase({dist[to],to});
dist[to] = dist[ver]+weight;
st.insert({dist[to],to});
}
}
}
if(dist[e]!=inf) {
cout << "escaped\n";
continue;
}
int mn = 1e18;
for(int i = 1;i<=s;i++) {
if(dist[a[i]]!=inf) {
mn = min(mn,dist[a[i]]);
}
}
if(mn == 1e18) {
cout << "oo\n";
} else {
cout << mn << "\n";
}
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tt=1;
//cin >> tt;
while(tt--) {
solve();
}
return 0;
}
