#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
int n,q,parent[100005],root,niv[100005],leaves[100005],nr[100005],topar[100005],where[100005],poz[100005],ans;
vector<int> vals;
int pathpar[100005];
set<int> used;
int nrleaves,nrpaths;
bool isheavy[100005];
vector<pii> muchii[100005];
vector<int> path[100005];
vector<vector<int>> arb,toprop,good;
void prop(int index,int nod,int st,int dr)
{
int mij=(st+dr)/2;
int lg=mij-st+1;
int nr=arb[index][nod*2];
arb[index][nod*2]=lg-nr;
toprop[index][nod*2]++;
toprop[index][nod*2]%=2;
lg=dr-mij;
nr=arb[index][nod*2+1];
arb[index][nod*2+1]=lg-nr;
toprop[index][nod*2+1]++;
toprop[index][nod*2+1]%=2;
}
void update(int index,int nod,int st,int dr,int a,int b, int val)
{
if(st!=dr&&toprop[index][nod]==1)
prop(index,nod,st,dr);
toprop[index][nod]=0;
if(st>=a&&dr<=b)
{
int lg=dr-st+1;
int nr=arb[index][nod];
arb[index][nod]=lg-nr;
ans-=(nr*1+(lg-nr)*2);
ans+=(lg-nr)*1+nr*2;
toprop[index][nod]++;
toprop[index][nod]%=2;
return;
}
int mij=(st+dr)/2;
if(a<=mij)
update(index,nod*2,st,mij,a,b,val);
if(b>mij)
update(index,nod*2+1,mij+1,dr,a,b,val);
arb[index][nod]=(arb[index][nod*2]+arb[index][nod*2+1]);
}
void dfs(int nod)
{
if(niv[nod]==0)
niv[nod]=1;
nr[nod]=1;
if(muchii[nod].size()==1)
{
leaves[nod]=1;
nr[nod]=1;
nrleaves++;
return;
}
for(auto i:muchii[nod])
if(i.first!=parent[nod])
{
topar[i.first]=i.second;
niv[i.first]=niv[nod]+1;
parent[i.first]=nod;
dfs(i.first);
nr[nod]+=nr[i.first];
leaves[nod]+=leaves[i.first];
}
int maxim=0,index=0;
for(auto i:muchii[nod])
if(i.first!=parent[nod])
if(nr[i.first]>maxim)
{
maxim=nr[i.first];
index=i.second;
}
isheavy[index]=1;
}
void build_path()
{
for(int i=1;i<=n;i++)
{
bool found=0;
for(auto j:muchii[i])
if(j.first!=parent[i])
if(isheavy[j.second])
found=1;
if(!found)
{
nrpaths++;
path[nrpaths].push_back(0);
path[nrpaths].push_back(i);
where[i]=nrpaths;
poz[i]=1;
int nod=i;
while(isheavy[topar[nod]])
{
nod=parent[nod];
path[nrpaths].push_back(nod);
poz[nod]=path[nrpaths].size()-1;
where[nod]=nrpaths;
}
int last=path[nrpaths][path[nrpaths].size()-1];
pathpar[nrpaths]=parent[last];
}
}
arb.resize(nrpaths+1);
toprop.resize(nrpaths+1);
good.resize(nrpaths+1);
for(int i=1;i<=nrpaths;i++)
{
int lg=path[i].size();
arb[i].resize(5*(lg+1));
toprop[i].resize(5*(lg+1));
for(int j=1;j<=5*lg;j++)
arb[i][j]=toprop[i][j]=0;
good[i].resize(5*(lg+1));
for(int j=1;j<lg;j++)
{
int nod=path[i][j];
if(leaves[nod]%2==1)
update(i,1,1,lg-1,j,j,1);
}
}
}
void plsupdate(int nod)
{
while(nod>0)
{
int p=poz[nod];
int index=where[nod];
int lg=path[index].size();
lg--;
update(index,1,1,lg,p,lg,1);
int last=path[index][path[index].size()-1];
nod=pathpar[index];
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin>>n>>q;
ans=2*n;
for(int i=1;i<n;i++)
{
int a,b;
cin>>a>>b;
muchii[a].push_back({b,i});
muchii[b].push_back({a,i});
}
for(int i=1;i<=n;i++)
if(muchii[i].size()>1)
{
root=i;
break;
}
dfs(root);
build_path();
//cout<<ans-(nrpaths%2==0?2:1)<<'\n';
while(q--)
{
int m;
cin>>m;
used.clear();
vals.clear();
for(int i=1;i<=m;i++)
{
int nod;
cin>>nod;
bool ok=0;
if(nod==3&&ans>12)
ok=1;
vals.push_back(nod);
ans++;
bool fnd=0;
if(muchii[nod].size()==1&&used.find(nod)==used.end())
fnd=1;
else
{
plsupdate(nod);
nrleaves++;
}
used.insert(nod);
}
if(nrleaves%2==1)
cout<<-1<<'\n';
else
cout<<ans-2<<'\n';
used.clear();
for(int nod:vals)
{
ans--;
bool fnd=0;
if(muchii[nod].size()==1&&used.find(nod)==used.end())
fnd=1;
else
{
plsupdate(nod);
nrleaves--;
}
used.insert(nod);
}
}
return 0;
}
