#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int n,q;
vector<int> dsk[N];
int leaves[N];
int sz[N], parv[N], depthv[N];
int chainh[N], chainid[N], pos[N], ar[N];
int curpos=1, curchain=1;
int st[4*N], lazy[4*N];
int R;
void dfs_leaves(int u,int p,int root){
if(dsk[u].size()==1 && u!=root) leaves[u]=1; else leaves[u]=0;
for(int v:dsk[u]) if(v!=p){
dfs_leaves(v,u,root);
leaves[u]+=leaves[v];
}
}
void dfs_sz(int u,int p){
sz[u]=1;
for(int v:dsk[u]) if(v!=p){
parv[v]=u;
depthv[v]=depthv[u]+1;
dfs_sz(v,u);
sz[u]+=sz[v];
}
}
void hld(int u,int p){
if(!chainh[curchain]) chainh[curchain]=u;
chainid[u]=curchain;
pos[u]=curpos;
ar[curpos]=u;
curpos++;
int heavy=0;
for(int v:dsk[u]) if(v!=p){
if(heavy==0 || sz[v]>sz[heavy]) heavy=v;
}
if(heavy) hld(heavy,u);
for(int v:dsk[u]) if(v!=p && v!=heavy){
curchain++;
hld(v,u);
}
}
void build(int id,int l,int r){
if(l==r){
st[id] = (leaves[ar[l]] % 2 == 0);
return;
}
int mid = (l + r) >> 1;
build(id<<1,l,mid);
build(id<<1|1,mid+1,r);
st[id] = st[id<<1] + st[id<<1|1];
}
void down(int id,int l,int r){
if(!lazy[id]) return;
int mid = (l + r) >> 1;
int left = id<<1, right = id<<1|1;
st[left] = (mid - l + 1) - st[left];
lazy[left] ^= 1;
st[right] = (r - mid) - st[right];
lazy[right] ^= 1;
lazy[id]=0;
}
void update_seg(int id,int l,int r,int x,int y){
if(l>y || x>r) return;
if(x<=l && r<=y){
st[id] = (r - l + 1) - st[id];
lazy[id] ^= 1;
return;
}
int mid = (l + r) >> 1;
down(id,l,r);
update_seg(id<<1,l,mid,x,y);
update_seg(id<<1|1,mid+1,r,x,y);
st[id] = st[id<<1] + st[id<<1|1];
}
int get_seg(int id,int l,int r,int x,int y){
if(l>y || x>r) return 0;
if(x<=l && r<=y) return st[id];
int mid = (l + r) >> 1;
down(id,l,r);
return get_seg(id<<1,l,mid,x,y) + get_seg(id<<1|1,mid+1,r,x,y);
}
int lca(int u,int v){
while(chainid[u] != chainid[v]){
if(chainid[u] > chainid[v]) u = parv[chainh[chainid[u]]];
else v = parv[chainh[chainid[v]]];
}
if(depthv[u] < depthv[v]) return u;
return v;
}
void updatePath(int u,int v){
int L = lca(u,v);
while(chainid[u] != chainid[L]){
update_seg(1,1,R,pos[chainh[chainid[u]]], pos[u]);
u = parv[chainh[chainid[u]]];
}
while(chainid[v] != chainid[L]){
update_seg(1,1,R,pos[chainh[chainid[v]]], pos[v]);
v = parv[chainh[chainid[v]]];
}
if(depthv[u] < depthv[v]){
update_seg(1,1,R,pos[u]+1,pos[v]);
} else {
update_seg(1,1,R,pos[v]+1,pos[u]);
}
}
int deg[N], cnt[N];
bool isLeaf[N];
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin>>n>>q;
for(int i=1;i<n;i++){int u,v;cin>>u>>v;dsk[u].push_back(v);dsk[v].push_back(u);}
int root=1;
for(int i=1;i<=n;i++) if(dsk[i].size()>1) {root=i;break;}
dfs_leaves(root,0,root);
depthv[root]=0; parv[root]=0;
dfs_sz(root,0);
hld(root,0);
R = curpos - 1;
build(1,1,R);
int cntLeaves=0;
for(int i=1;i<=n;i++){ deg[i]=dsk[i].size(); if(deg[i]<=1){ cntLeaves++; isLeaf[i]=true;} else isLeaf[i]=false; }
while(q--){
int z;cin>>z; vector<int> a(z);
for(int i=0;i<z;i++) cin>>a[i];
int curLeaves = cntLeaves;
vector<int> s;
for(int i=0;i<z;i++){
s.push_back(a[i]);
if(deg[a[i]]<=1) curLeaves--;
curLeaves++;
cnt[a[i]]++;
deg[a[i]]++;
}
sort(s.begin(), s.end()); s.erase(unique(s.begin(), s.end()), s.end());
if(curLeaves & 1){
cout<<-1<<"\n";
for(auto x:s){ deg[x]=dsk[x].size(); cnt[x]=0; }
continue;
}
for(auto x:s){
if(isLeaf[x] && ((cnt[x] & 1) == 0)) updatePath(1,x);
else if(!isLeaf[x] && ((cnt[x] & 1) == 1)) updatePath(1,x);
}
cout<<n + z - 2 + st[1]<<"\n";
for(auto x:s){
if(isLeaf[x] && ((cnt[x] & 1) == 0)) updatePath(1,x);
else if(!isLeaf[x] && ((cnt[x] & 1) == 1)) updatePath(1,x);
}
for(auto x:s){ deg[x]=dsk[x].size(); cnt[x]=0; }
}
return 0;
}
