#include<bits/stdc++.h>
using namespace std;
void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
cerr << h; if(sizeof...(t)) cerr << ", ";
DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL
#define FOR(i,a,b) for(int i = (a) ; i<(b) ; i++)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for(int i = (b)-1 ; i>=(a) ; i--)
#define R0F(i,a) ROF(i,0,a)
#define each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;
void setIO(string NAME = "") {
cin.tie(0)->sync_with_stdio(0);
if(sz(NAME)) {
freopen((NAME + ".inp").c_str(),"r",stdin);
freopen((NAME + ".out").c_str(),"w",stdout);
}
}
#define f first
#define s second
tcT> bool ckmin(T&a, const T&b) {
return b < a ? a = b, 1 : 0;
}
const int MX = 1e5+5, LG = 17;
const ll INF = 1e18;
int N, S, Q, E, jmp[MX][LG], tin[MX], tout[MX], timer_;
ll dp[MX], mnjmp[MX][LG], dep[MX];
pi eds[MX];
V<pi> adj[MX];
void dfs(int u, int p) {
tin[u] = ++timer_;
if(dp[u] == -1) dp[u] = dep[u];
each(v, adj[u]) if(v.f != p) {
dep[v.f] = dep[u] + v.s;
dfs(v.f, u);
ckmin(dp[u], dp[v.f]);
}
tout[u] = timer_;
}
void DFS(int u, int p) {
mnjmp[u][0] = min(dp[u], dp[p]);
FOR(i,1,LG) {
jmp[u][i] = jmp[jmp[u][i-1]][i-1];
mnjmp[u][i] = min(mnjmp[u][i-1], mnjmp[jmp[u][i-1]][i-1]);
}
each(v, adj[u]) if(v.f != p) {
jmp[v.f][0] = u;
DFS(v.f, u);
}
}
bool isa(int u, int v) { return tin[u] <= tin[v] && tout[v] <= tout[u]; }
void solve() {
cin>>N>>S>>Q>>E;
memset(dp, 0x3f, sizeof dp);
memset(mnjmp, 0x3f, sizeof mnjmp);
F0R(_,N-1) {
int u,v,w;
cin>>u>>v>>w;
adj[u].pb({v,w});
adj[v].pb({u,w});
eds[_+1] = {u,v};
}
F0R(i,S) {
int x; cin>>x;
dp[x] = -1;
}
//dbg(N);
dfs(E, -1);
FOR(i,1,N+1) dp[i] -= 2*dep[i];
jmp[E][0] = E;
DFS(E,E);
//dbg(dp[3]);
while(Q-->0) {
int I, R; cin>>I>>R;
int x = eds[I].f, y = eds[I].s;
if(dep[x] > dep[y]) swap(x,y);
if(isa(y, R)) {
ll ans = dp[R];
int cur = R;
R0F(i,LG) if(isa(y,jmp[R][i])) ckmin(ans, mnjmp[R][i]), R = jmp[R][i];
if(ans>=INF) {
cout << "oo\n";
continue;
}
cout << ans + dep[cur] << nl;
}
else {
cout << "escaped\n";
}
}
}
int main() {
setIO();
int t=1;
//cin>>t;
while(t-->0) {
solve();
}
return 0;
}
