#include <bits/stdc++.h>
using namespace std;
#define int int64_t
#define pii array<int,2>
#define tii array<int,3>
signed main() {
ios::sync_with_stdio(false);
cin.tie(0);
int n,s,q,e;cin>>n>>s>>q>>e;
e--;
vector<vector<pii>> g(n);
vector<tii> edg;
for (int i=1;i<n;i++) {
int a,b,w;cin>>a>>b>>w;
a--;b--;
g[a].push_back({b,w});
g[b].push_back({a,w});
edg.push_back({a,b,w});
}
vector<bool> shop(n,false);
for (int i=0;i<s;i++) {
int c;cin>>c;shop[--c]=true;
}
vector<int> dp(n,1e16);
vector<vector<int>> lft(n, vector<int>(20,-1)), weight(n, vector<int>(20,0)), shr(n, vector<int>(20,1e16));
vector<int> d(n,0);
function<void(int,int)> dfs=[&](int node, int pv) {
if (shop[node]) {
dp[node]=0;
}
for (auto [x, w]:g[node]) {
if (x==pv)continue;
d[x]=d[node]+1;
lft[x][0]=node;
weight[x][0]=w;
dfs(x,node);
dp[node]=min(dp[node],dp[x]+w);
}
};
dfs(e,-1);
for (int i=0;i<n;i++) {
if (e == i) continue;
shr[i][0] = dp[lft[i][0]] + weight[i][0];
}
for (int j=1;j<20;j++) {
for (int i=0;i<n;i++) {
lft[i][j]=lft[i][j-1];
if (lft[i][j]!=-1) {
lft[i][j]=lft[lft[i][j]][j-1];
weight[i][j]=weight[i][j-1]+weight[lft[i][j-1]][j-1];
shr[i][j] = min(shr[i][j-1], shr[lft[i][j-1]][j-1] + weight[i][j-1]);
}
}
}
function<int(int,int)> jmp=[&](int a,int steps)->int {
int cnt=0;
while (steps) {
if ((steps&1)==1) {
a=lft[a][cnt];
if (a==-1)return-1;
}
cnt++;steps>>=1;
}
return a;
};
function<int(int,int)> lca=[&](int a,int b) -> int {
if (d[a]<d[b])swap(a,b);
a=jmp(a,d[a]-d[b]);
if(a==b)return a;
for (int i=19;i>=0;i--) {
if(lft[a][i]!=lft[b][i]) {
a=lft[a][i];
b=lft[b][i];
}
}
return lft[a][0];
};
function<int(int,int)> shortest=[&](int a, int steps) -> int {
int mn = dp[a];
int pWeight=0;
int cnt=0;
while (steps) {
if ((steps&1)==1) {
int candidate = pWeight + shr[a][cnt];
mn = min(mn, candidate);
pWeight += weight[a][cnt];
a=lft[a][cnt];
}
steps>>=1;cnt++;
}
return mn;
};
while (q--) {
int i,r;cin>>i>>r;
i--;r--;
int n1=edg[i][0], n2=edg[i][1];
if (d[n1] <= d[r] && d[n2] <= d[r] && lca(n1, r) == n1 && lca(n2, r) == n2) {
int low=max(d[n1], d[n2]);
int mn = shortest(r, d[r]-low);
if (mn >= 1e16) {
cout<<"oo\n";
}
else {
cout<<mn<<"\n";
}
}
else {
cout<<"escaped\n";
}
}
}
