#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define vl vector<ll>
#define pi pair<int, int>
#define pl pair<ll,ll>
#define all(x) (x).begin(),(x).end()
const int maxn=1e5+10;
const int logg=ceil(log2(maxn));
vector<vector<pl>> graph(maxn);
vector<pi> edges(maxn);
vi tin(maxn),tout(maxn);
int timer=0;
vl dst(maxn,1e18);
vl depth(maxn,0);
vector<vi> up(maxn,vi(logg+1));
vector<vl> vals(maxn,vl(logg+1));
void dfs(int cur, int prev, ll len) {
tin[cur]=timer++;
depth[cur]=depth[prev]+len;
up[cur][0]=prev;
for (int i=1; i<=logg; i++) {
up[cur][i]=up[up[cur][i-1]][i-1];
}
for (auto [to,w]:graph[cur]) {
if (prev==to) {
continue;
}
dfs(to,cur,w);
dst[cur]=min(dst[cur],dst[to]+w);
}
vals[cur][0]=dst[cur];
tout[cur]=timer;
}
void dfs2(int cur, int prev) {
for (int i=1; i<=logg; i++) {
vals[cur][i]=min(vals[cur][i-1],vals[up[cur][i-1]][i-1]+depth[cur]-depth[up[cur][i-1]]);
}
for (auto [to,w]:graph[cur]) {
if (prev==to) {
continue;
}
dfs2(to,cur);
}
}
bool is_root(int a, int b) {
return (tin[a]<=tin[b] && tout[b]<=tout[a]);
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n,s,q,e;
cin >> n >> s >> q >> e;
e--;
int a,b;
ll c;
for (int i=0; i<n-1; i++) {
cin >> a >> b >> c;
edges[i]={--a,--b};
graph[a].pb({b,c});
graph[b].pb({a,c});
}
for (int i=0; i<s; i++) {
cin >> a;
dst[--a]=0;
}
dfs(e,e,0);
dfs2(e,e);
for (int i=0; i<q; i++) {
cin >> a >> b;
a--;
b--;
int l=edges[a].fi;
int r=edges[a].se;
if (depth[l]<depth[r]) {
swap(l,r);
}
if (!is_root(l,b)) {
cout << "escaped\n";
continue;
}
l=b;
ll ans=1e18;
for (int j=logg; j>=0; j--) {
if (!is_root(up[l][j],r)) {
ans=min(ans,vals[l][j]+depth[b]-depth[l]);
l=up[l][j];
}
}
ans=min(ans,vals[l][0]+depth[b]-depth[l]);
if (ans==1e18) {
cout << "oo\n";
}
else {
cout << ans << '\n';
}
}
return 0;
}
