#include <bits/stdc++.h>
#define NMAX 100000
#define LOG 20
#define ll long long int
#define BASE 1024
#define MOD 1000000009
using namespace std;
ifstream fin("cod.in");
ofstream fout("cod.out");
ll minDist[NMAX+1],dist[NMAX+1];
int isShop[NMAX+1];
vector<pair<int,int>> adj[NMAX+1];
pair<int,int> edges[NMAX+1];
int d[NMAX+1];
pair<int,ll> p[NMAX+1][LOG+1];
int n,s,q,e;
void dfs(int x,int t)
{
minDist[x] = isShop[x] ? 0 : 1e17;
p[x][0].first = t;
d[x] = d[t] + 1;
for(auto [y,c] : adj[x])
{
if(y!=t)
{
dist[y] = dist[x] + c;
dfs(y,x);
minDist[x] = min(minDist[x], minDist[y] + c);
}
}
}
pair<int,ll> kth(int x,int k)
{
ll mn = minDist[x] == 1e17 ? 1e17 : minDist[x] - dist[x];
for(int i=LOG;i>=0;i--)
{
if(d[x]-(1<<i) >= k)
{
mn = min(mn,p[x][i].second);
x = p[x][i].first;
}
}
return {x,mn};
}
int main()
{
cin >> n >> s >> q >> e;
for(int i=1;i<n;i++)
{
int a,b,w;
cin >> a >> b >> w;
edges[i] = {a,b};
adj[a].push_back({b,w});
adj[b].push_back({a,w});
}
for(int i=1;i<=s;i++)
{
int x;
cin >> x;
isShop[x] = 1;
}
dfs(e,0);
for(int i=1;i<=n;i++)
{
p[i][0].second = min(minDist[p[i][0].first] - dist[p[i][0].first] , minDist[i] == 1e17 ? (ll)1e17 : minDist[i] - dist[i]);
}
for(int j=1;j<=LOG;j++)
{
for(int i=1;i<=n;i++)
{
p[i][j].first = p[p[i][j-1].first][j-1].first;
p[i][j].second = min(p[i][j-1].second,p[p[i][j-1].first][j-1].second);
}
}
for(int i=1;i<n;i++)
{
if(d[edges[i].first] > d[edges[i].second])
{
swap(edges[i].first,edges[i].second);
}
}
while(q--)
{
int i,x;
cin >> i >> x;
int t = edges[i].second;
if(d[t]<=d[x] && kth(x,d[t]).first==t)
{
ll mn = kth(x,d[t]).second;
if(mn==1e17)
{
cout << "oo\n";
}
else
{
cout << mn+dist[x] << '\n';
}
}
else
{
cout << "escaped\n";
}
}
}
