#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
using llu=unsigned long long;
using ll=long long;
using ld=long double;
using pir=pair<ll,ll>;
using vl=vector<ll>;
using sl=set<ll>;
using msl=multiset<ll>;
using prq=priority_queue<ll>;
using prqi=priority_queue<ll,vector<ll>,greater<ll>>;
using ma=map<ll,ll>;
using vp=vector<pair<ll,ll>>;
using vvl=vector<vector<ll>>;
using vvp=vector<vector<pair<ll,ll>>>;
using sp=set<pair<ll,ll>>;
using msp=multiset<pair<ll,ll>>;
#define nfs string::npos
#define count1(n) __builtin_popcountll(n)
#define last1(n) __builtin_ctzll(n)
#define first1(n) 63-__builtin_clzll(n)
#define maxi(v) max_element(all(v))
#define mini(v) min_element(all(v))
#define lb(n) lower_bound(n)
#define ub(n) upper_bound(n)
#define lbd(v,n) lower_bound(all(v),n)
#define ubd(v,n) upper_bound(all(v),n)
#define bins(v,n) binary_search(all(v),n)
#define fr(i,a,b) for(i=a;i<=b;i++)
#define fv(i,a,b) for(i=a;i>=b;i--)
#define f(i,n) for(i=0;i<n;i++)
#define fn(i,n) for(i=n-1;i>=0;i--)
#define pb push_back
#define ppb pop_back
#define all(v) v.begin(),v.end()
#define g(v,n) vl v(n); f(_,n) cin>>v[_]
#define bs(n,x) bitset<n> (x).to_string()
#define invp(v,n) vp v;f(_,n) cin>>v[_].first>>v[_].second
#define seev(v) for(auto ggg:v) cout<<ggg<<"-"
#define print(v) for(auto ggg:v) cout<<ggg<<" "
const ll inf=4e18;
const ll mod=1000000007;
const ll mod2=998244353;
ll power(ll a,ll b,ll p=inf)
{
ll res=1;a%=p;
while(b>0)
{
if(b%2==1)
res=(res*a)%p;
a=(a*a)%p;
b=b/2;
}
return res;
}
ll log(ll n,ll k)
{
ll a=k,b=0;
while(a<=n)
a*=k,b++;
return b;
}
ll todec(ll n,string s)
{
ll i,k=0;
f(i,n)
if(s[i]=='1')
k+=1LL<<(n-i-1);
return k;
}
bool vps(const pair<ll,ll> &a,const pair<ll,ll> &b)
{
return (a.second<b.second);
}
bool fts(const pair<ll,ll> &a,const pair<ll,ll> &b)
{
if(a.first!=b.first)
return (a.first<b.first);
return (a.second>b.second);
}
vl segtree(vl& v)
{
ll i,n=v.size();
ll p=power(2,log(n-1,2)+1);
f(i,p-n)
v.pb(0);
n=v.size();
vl sgt(2*n);
fr(i,n,2*n-1)
sgt[i]=v[i-n];
fn(i,n)
sgt[i]=max(sgt[2*i],sgt[2*i+1]);
return sgt;
}
void update(vl& sgt,ll k,ll x)
{
ll n=sgt.size()/2;k+=n;
sgt[k]=x;
for(k=k/2;k>0;k/=2)
sgt[k]=max(sgt[2*k],sgt[2*k+1]);
}
ll query(vl& sgt,ll l,ll r)
{
ll n=sgt.size()/2,q=-inf;
l+=n;r+=n;
while(l<=r)
{
if(l%2==1)
q=max(q,sgt[l++]);
if(r%2==0)
q=max(q,sgt[r--]);
l/=2;r/=2;
}
return q;
}
vl level(vvp& v,ll root)
{
ll n=v.size()-1;
vl lvl(n+1),vt(n+1);
function<void(ll)> dfs=[&](ll nd)
{
vt[nd]=1;
for(auto g:v[nd])
{
if(vt[g.first])
continue;
lvl[g.first]=lvl[nd]+1;
dfs(g.first);
}
};
dfs(root);
return lvl;
}
pir merge(pir a,pir b)
{
vl v={a.first,a.second,b.first,b.second};
sort(all(v));
return {v[0],v[1]};
}
vvl binup(vvp& v,ll root,vvl& data,vl& ht,vl& lvl)
{
ll i,j,n=v.size()-1;
ll m=first1(n)+1;
vvl bin(m,vl(n+1));
data.resize(m,vl(n+1,inf));
vl vt(n+1);
function<void(ll)> dfs=[&](ll nd)
{
vt[nd]=1;
for(auto g:v[nd])
{
if(vt[g.first])
continue;
bin[0][g.first]=nd;
dfs(g.first);
}
};
dfs(root);
fr(j,1,m-1)
fr(i,1,n)
bin[j][i]=bin[j-1][bin[j-1][i]];
vp info(n+1,{inf,inf});
fr(i,1,n)
{
info[i]={ht[i]-lvl[i],inf};
for(auto g:v[i])
if(bin[0][g.first]==i)
info[i]=merge(info[i],{ht[g.first]-lvl[g.first]+2*g.second,inf});
}
fr(i,1,n)
{
data[0][i]=info[bin[0][i]].first;
ll x=0;
for(auto g:v[bin[0][i]])
if(g.first==i)
x=g.second;
if(info[bin[0][i]].first==ht[i]-lvl[i]+2*x)
data[0][i]=info[bin[0][i]].second;
}
fr(j,1,m-1)
fr(i,1,n)
data[j][i]=min(data[j-1][i],data[j-1][bin[j-1][i]]);
return bin;
}
ll lca(vvl& bin,vl& lvl,ll a,ll b)
{
ll i,lc,m=bin.size();
if(lvl[a]<lvl[b])
swap(a,b);
fn(i,m)
if(lvl[a]-(1ll<<i)>=lvl[b])
a=bin[i][a];
if(a==b)
return a;
fn(i,m)
if(bin[i][a]!=bin[i][b])
a=bin[i][a],b=bin[i][b];
return bin[0][a];
}
void solve(ll tc)
{
ll n,m,k=0,j=0,i=0,x=0,y=0,z=0,p=0,q=0,l=0,sum=0,temp=1,flag=0,a=0,b=0,c=0,d=1,r=0,mn=inf,mx=-inf,_,__,mid;
string s1,s2,s3,s;char ch;
cin>>n>>m>>q>>p;
vvp v(n+1);
vp edge(n);
f(i,n-1)
{
cin>>x>>y>>d;
edge[i+1]={x,y};
v[x].pb({y,d});
v[y].pb({x,d});
}
vl vt(n+1),ht(n+1,inf),lvl(n+1);
f(i,m)
{
cin>>x;ht[x]=0;
}
vl tin(n+1),tout(n+1);c=0;
function<void(ll)>dfs=[&](ll nd)
{
vt[nd]=1;
tin[nd]=++c;
for(auto g:v[nd])
{
if(vt[g.first])
continue;
lvl[g.first]=lvl[nd]+g.second;
dfs(g.first);
ht[nd]=min(ht[nd],ht[g.first]+g.second);
}
tout[nd]=c;
};
dfs(p);
ht[0]=inf;
vvl data;
vvl bin=binup(v,p,data,ht,lvl);
vl lvvl=level(v,p);
while(q--)
{
cin>>p>>x;c=x;
x=edge[p].first;
y=edge[p].second;
if(tin[y]>tin[x])
swap(x,y);
if(!(tin[c]>=tin[x]&&tin[c]<=tout[x]))
{
cout<<"escaped"<<endl;
continue;
}
k=lvvl[c]-lvvl[x];x=c;
mn=ht[x]-lvl[x];
s=bs(20,k);
reverse(all(s));
f(i,20)
{
if(s[i]=='1')
{
mn=min(mn,data[i][x]);
x=bin[i][x];
}
}
if(mn+lvl[c]==inf)
cout<<"oo"<<endl;
else
cout<<mn+lvl[c]<<endl;
}
}
//Use variables correctly
//Check for boundary conditions
//Write the step statement in while loops
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
ll t=1;
// cin>>t;
while(t--)
{
solve(t);
cout<<endl;
}
return 0;
}
