#include <bits/stdc++.h>
using namespace std;
long long n, nr, q, t, e;
vector<pair<int, int>> edges;
bool isShop[100005];
long long d[100005];
long long dp[100005];
int in[100005], out[100005];
vector<pair<long long, long long>> v[100005];
vector<pair<int, int>> qv[100005];
long long ans[100005];
vector<long long> seg;
void upd(int stt, int drt, int st, int dr, int p, long long val)
{
if(stt == st && drt == dr)
{
seg[p] = min(seg[p], val);
return;
}
int mij = (st + dr)/2;
if(drt <= mij)
upd(stt, drt, st, mij, 2*p, val);
else if(stt > mij)
upd(stt, drt, mij+1, dr, 2*p+1, val);
else
{
upd(stt, mij, st, mij, 2*p, val);
upd(mij+1, drt, mij+1, dr, 2*p+1, val);
}
}
long long query(int i, int st, int dr, int p)
{
if(st == dr)
return seg[p];
int mij = (st+dr)/2;
if(i <= mij)
return min(seg[p], query(i, st, mij, 2*p));
else
return min(seg[p], query(i, mij+1, dr, 2*p+1));
}
void dfs(int p, int par)
{
t++;
in[p] = t;
if(isShop[p])
dp[p] = 0;
else
dp[p] = 1e18;
for(auto it : v[p])
{
if(it.first == par)
continue;
d[it.first] = d[p] + it.second;
dfs(it.first, p);
dp[p] = min(dp[p], dp[it.first] + it.second);
}
out[p] = t;
}
void calc(int p, int par)
{
for(auto it : v[p])
{
if(it.first == par)
continue;
calc(it.first, p);
}
upd(in[p], out[p], 1, n, 1, dp[p] - d[p]);
for(auto it : qv[p])
{
int pozQ = it.first;
int idQ = it.second;
if(in[p] <= in[pozQ] && in[pozQ] <= out[p])
ans[idQ] = query(in[pozQ], 1, n, 1) + d[pozQ];
else
ans[idQ] = -1;
}
}
int main()
{
cin>>n>>nr>>q>>e;
seg.resize(4*n+4);
fill(seg.begin(), seg.end(), 1e18);
edges.push_back({0, 0});
for(int i=1;i<n;i++)
{
long long x, y, w;
cin>>x>>y>>w;
v[x].push_back({y, w});
v[y].push_back({x, w});
edges.push_back({x, y});
}
for(int i=1;i<=nr;i++)
{
int x;
cin>>x;
isShop[x] = true;
}
dfs(e, 0);
for(int i=1; i<=n; i++)
upd(in[i], in[i], 1, n, 1, dp[i] - d[i]);
for(int i=1;i<=q;i++)
{
int id, p;
cin>>id>>p;
int x = edges[id].first;
int y = edges[id].second;
if(d[x] > d[y])
swap(x, y);
qv[y].push_back({p, i});
}
calc(e, 0);
for(int i=1;i<=q;i++)
{
if(ans[i] == -1)
cout<<"escaped\n";
else
{
if(ans[i] == 1e18)
cout<<"oo\n";
else
cout<<ans[i]<<'\n';
}
}
return 0;
}
