#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define pb push_back
#define all(x) x.begin(),x.end()
#define int long long
#define ar array
#define mrand(a, b) uniform_int_distribution<int>(a, b)(rng)
template<class T>bool umax(T &a,T b){if(a<b){a=b;return true;}return false;}
template<class T>bool umin(T &a,T b){if(b<a){a=b;return true;}return false;}
template<class T> using ste = tree<T, null_type, less_equal<T>,
rb_tree_tag, tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const int N = 600000 + 5;
const int LOG = 20;
const int INF = (1LL<<60);
int n,m,k;
vector<int> tin(N), tout(N), dep(N), dp(N), type(N);
vector<ar<int,2>> g[N];
int p[N][LOG], val[N][LOG];
int timer;
int dfs(int x, int pr){
tin[x] = ++timer;
p[x][0] = pr;
for(int i = 1;i<LOG;i++) p[x][i] = p[p[x][i-1]][i-1];
int mn = INF;
for(auto [to, cost] : g[x]){
if(to == pr) continue;
dep[to] = dep[x] + cost;
umin(mn, dfs(to, x));
}
if(type[x]) umin(mn, dep[x]);
if(mn == INF) dp[x] = INF;
else dp[x] = mn - 2 * dep[x];
tout[x] = ++timer;
return mn;
}
void dfs2(int x, int pr){
val[x][0] = min(dp[x], dp[pr]);
for(int i = 1;i<LOG;i++) val[x][i] = min(val[x][i-1], val[p[x][i-1]][i-1]);
for(auto [to, cost] : g[x]){
if(to == pr) continue;
dfs2(to, x);
}
}
bool is_anc(int a, int b){
return tin[a] <= tin[b] && tout[b] <= tout[a];
}
int getMinOnPath(int u, int anc){
if(u == anc) return dp[anc];
int res = dp[u];
for(int i = LOG-1;i>=0;i--){
if(!is_anc(p[u][i], anc)){
umin(res, val[u][i]);
u = p[u][i];
}
}
umin(res, val[u][0]);
umin(res, dp[anc]);
return res;
}
void solve(){
int q;
cin >> n >> m >> q >> k;
for(int i=1;i<=n;i++){
g[i].clear();
type[i] = 0;
dep[i] = 0;
dp[i] = INF;
tin[i] = tout[i] = 0;
for(int j=0;j<LOG;j++) p[i][j] = i, val[i][j] = INF;
}
timer = 0;
vector<ar<int,2>> vs;
for(int i = 2;i<=n;i++){
int a,b,c;
cin >> a >> b >> c;
g[a].pb({b, c});
g[b].pb({a, c});
vs.pb({a, b});
}
for(int i = 1;i<=m;++i){
int a;
cin >> a;
type[a] = 1;
}
dfs(k, k);
dfs2(k, k);
while(q--){
int a,b;
cin >> a >> b;
a -= 1;
int e1 = vs[a][0], e2 = vs[a][1];
if(dep[e1] >= dep[e2]) a = e1;
else a = e2;
if(!is_anc(a, b)){
cout << "escaped\n";
continue;
}
int ans = getMinOnPath(b, a);
if(ans >= INF/4){
cout << "oo\n";
} else {
cout << (ans + dep[b]) << "\n";
}
}
}
signed main(){
ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);
int tt=1;
while(tt--) solve();
return 0;
}
