#include <bits/stdc++.h>
using namespace std;
const int N=1e5;
vector<int> adj[N+1];
int la[N+1], cl[N+1];
int vis[N+1],chi[N+1];
int pa[N+1],n,m,id[N+1];
struct seg
{
int odd=0,even=0,lazy=0;
}st[4*N+1];
void dfs(int u)
{
chi[u]=1;
cl[u]=0;
vis[u]=1;
for(int v : adj[u])
{
if(vis[v]) continue;
pa[v]=u;
dfs(v);
chi[u]+=chi[v];
cl[u]+=cl[v];
cl[u]%=2;
}
if(adj[u].size()==1)
cl[u]=1;
//cout << u << " "
}
int chead[N+1], cid[N+1], pos[N+1], ch=1, tme=0;
void hld(int u)
{
cid[u]=ch;
pos[u]=++tme;
id[tme]=cl[u];
int mx=0;
int k;
for(int v : adj[u])
{
if(v==pa[u]) continue;
if(mx<chi[v])
{
mx=chi[v];
k=v;
}
}
if(mx==0) return;
hld(k);
for(int v : adj[u])
{
if(v==k || v==pa[u]) continue;
ch++;
chead[ch]=v;
hld(v);
}
}
void push(int x)
{
if(st[x].lazy==0) return;
st[x].lazy=0;
st[x*2].lazy^=1;
st[x*2+1].lazy^=1;
swap(st[x*2].odd, st[x*2].even);
swap(st[x*2+1].odd, st[x*2+1].even);
}
void update(int x, int low, int hi, int i, int j)
{
if(low> hi || low > j || hi<i) return;
if(low>=i && hi<=j)
{
st[x].lazy^=1;
swap(st[x].odd, st[x].even);
return;
}
push(x);
int mid=low+hi>>1;
update(x*2,low,mid,i,j);
update(x*2+1,mid+1,hi,i,j);
st[x].odd=st[x*2].odd+st[x*2+1].odd;
st[x].even=st[x*2].even+st[x*2+1].even;
}
int get(int x, int low, int hi, int i)
{
if(low==hi) return st[x].odd;
int mid=low+hi>>1;
push(x);
if(i<=mid) return get(x*2,low,mid,i);
return get(x*2+1,mid+1,hi,i);
}
void updatetree(int u, int v)
{
while(cid[u]!=cid[v])
{
update(1,1,n,pos[chead[cid[v]]],pos[v]);
v=pa[chead[cid[v]]];
}
update(1,1,n,pos[u],pos[v]);
}
void build(int x, int low, int hi)
{
if(low==hi)
{
if(id[low])
{
st[x].odd=1;
}
else st[x].even=1;
return;
}
int mid=low+hi>>1;
build(x*2,low,mid);
build(x*2+1,mid+1,hi);
st[x].odd=st[x*2].odd+st[x*2+1].odd;
st[x].even=st[x*2].even+st[x*2+1].even;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m;
for(int i=1;i<n;++i)
{
int u,v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
int base;
for(int i=1;i<=n;++i)
{
if(adj[i].size()==1)
{
la[i]=1;
}
else
{
base=i;
}
}
dfs(base);
chead[1]=base;
hld(base);
build(1,1,n);
// for(int i=1;i<=n;++i) cout << cl[i] << " ";
// cout << '\n';
//cout << st[1].even<<"\n";
while(m--)
{
int k;
cin >> k;
vector<int> p;
for(int i=1;i<=k;++i)
{
int u;
cin >> u;
p.push_back(u);
if(la[u]==1)
{
la[u]=2;
}
else
{
updatetree(base,u);
}
}
if(get(1,1,n,pos[base]))
{
cout << -1 << '\n';
}
else
{
int cnt = st[1].even-1;
//cout << cnt << " ";
cout << n-1+cnt+k << '\n';
}
for(int u : p)
{
if(la[u]==2)
{
la[u]=1;
}
else
{
updatetree(base,u);
}
}
}
}
