#include <iostream>
#include <vector>
using namespace std;
int n, s, q, e;
bool shop[300005];
vector<pair<int,int>> adj[300005];
vector<pair<int,int>> edges;
long long dist [300005], tin[300005],tout[300005],close[300005];
vector<int> ord;
void dfs(int nod,int p)
{
ord.push_back(nod);
tin[nod] = ord.size();
for ( auto u : adj[nod])
{
if ( u.first != p)
{
dist[u.first] = dist[nod] + u.second;
dfs(u.first,nod);
}
}
if ( shop [nod] == 1 )
close[nod] =dist[nod];
else
close[nod] = 1e18;
for ( auto u :adj[nod])
if ( u.first != p )
close[nod] = min (close[nod], close[u.first]);
tout[nod] = ord.size();
}
long long jmp[300005][21] , mag[300005][21];
void lift(int nod ,int p)
{
jmp[nod][0] = p;
mag[nod][0] = close[nod];
for (int k = 1; k <= 19 ; k ++)
{
jmp[nod][k] = jmp[jmp[nod][k-1]][k-1];
mag[nod][k] = min(mag[nod][k-1] , mag[jmp[nod][k-1]][k-1]);
}
for ( auto u : adj[nod])
if ( u.first != p)
lift(u.first,nod);
}
long long cost(int nod ,int tg )
{
long long ans = 1e18;
int d = nod ;
for( int k = 18 ; k >= 0 ; k -- )
{
int a = jmp[d][k];
if ( tin[a] >= tin [tg] && tout[a] <= tout[tg] )
{
ans =min ( ans , mag[d][k]);
d = jmp[d][k];
}
}
ans = min ( ans , close[tg]);
return ans + dist[nod];
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >>n>>s>>q>>e;
for(int i = 1; i < n ; i ++ )
{
int a, b, c;
cin >> a>> b>> c;
adj[a].push_back({b,c});
adj[b].push_back({a,c});
edges.push_back({a,b});
}
for( int i = 1; i <= s; i ++)
{
int a;
cin >> a;
shop[a] =true;
}
dfs(e,0);
for ( int i = 1; i <= n ; i ++ )
close [i] -= 2 * dist[i];
lift(e,0);
for ( int i = 1; i <= q; i ++ )
{
int l , r;
cin >> l >> r;
l -- ;
int a = edges[l].first;
int b = edges[l].second;
int tg ;
if ( tin[a] <= tin[b] && tout[b] <= tout[a])
tg = b;
else
tg = a ;
if ( tin[r] < tin[tg] || tout[r] > tout[tg])
{
cout << "escaped"<< '\n';
continue;
}
long long ans = cost (r , tg);
if ( ans >= 1e15 )
{
cout << "oo" << '\n';
}
else
cout << ans << '\n' ;
}
return 0;
}
