#include <bits/stdc++.h>
#define DIM 100010
using namespace std;
int whatChain[DIM],chainFatherNode[DIM],level[DIM],positionInChain[DIM],Size[DIM];
int frunza[DIM],f[DIM],mrk[DIM],fth[DIM],g[DIM],v[DIM];
vector <int> chains[DIM],L[DIM];
set <int> w;
int nr_chains,n,q,i,j,x,y,m,rad;
struct segment_tree{
int cnt; /// cate noduri au nr par de frunze in subarborele lor
int lazy;
};
vector <segment_tree> aint[DIM];
void dfs (int nod, int tata){
Size[nod] = 1;
level[nod] = 1 + level[tata];
fth[nod] = tata;
int ok = 0;
for (auto vecin : L[nod])
if (vecin != tata){
ok = 1;
dfs (vecin,nod);
Size[nod] += Size[vecin];
f[nod] += f[vecin]; /// cate frunze am in subarborele lui nod
}
if (!ok){
nr_chains++;
chains[nr_chains].push_back(0);
chains[nr_chains].push_back(nod);
positionInChain[nod] = 1;
whatChain[nod] = nr_chains;
f[nod] = frunza[nod] = 1;
} else {
int maxi = 0, heavy_son = 0;
for (auto vecin : L[nod]){
if (vecin == tata)
continue;
if (Size[vecin] > maxi)
maxi = Size[vecin], heavy_son = vecin;
}
chains[whatChain[heavy_son]].push_back(nod);
whatChain[nod] = whatChain[heavy_son];
positionInChain[nod] = chains[whatChain[heavy_son]].size()-1;
for (auto vecin : L[nod]){
if (vecin != tata && vecin != heavy_son)
chainFatherNode[whatChain[vecin]] = nod;
}}}
void build (int chain, int nod, int st, int dr){
if (st == dr){
if (f[chains[chain][st]] % 2 == 0) /// are nr par de frunze
aint[chain][nod].cnt = 1;
return;
}
int mid = (st+dr)>>1;
build (chain,nod<<1,st,mid);
build (chain,(nod<<1)|1,mid+1,dr);
aint[chain][nod].cnt = aint[chain][nod<<1].cnt + aint[chain][(nod<<1)|1].cnt;
}
void update_lazy (int chain, int nod, int st, int dr){
if (!aint[chain][nod].lazy)
return;
if (st != dr){
int fiu_st = nod<<1, fiu_dr = (nod<<1)|1, mid = (st+dr)>>1;
aint[chain][fiu_st].cnt = mid - st + 1 - aint[chain][fiu_st].cnt;
aint[chain][fiu_st].lazy = 1 - aint[chain][fiu_st].lazy;
aint[chain][fiu_dr].cnt = dr - mid - aint[chain][fiu_dr].cnt;
aint[chain][fiu_dr].lazy = 1 - aint[chain][fiu_dr].lazy;
}
aint[chain][nod].lazy = 0;
}
void update (int chain, int nod, int st, int dr, int x, int y){
update_lazy (chain,nod,st,dr);
if (x <= st && dr <= y){
/// trb sa dau reverse
aint[chain][nod].cnt = (dr - st + 1) - aint[chain][nod].cnt;
aint[chain][nod].lazy = 1;
update_lazy (chain,nod,st,dr);
return;
}
int mid = (st+dr)>>1;
if (x <= mid)
update (chain,nod<<1,st,mid,x,y);
if (y > mid)
update (chain,(nod<<1)|1,mid+1,dr,x,y);
update_lazy (chain,nod<<1,st,mid);
update_lazy (chain,(nod<<1)|1,mid+1,dr);
aint[chain][nod].cnt = aint[chain][nod<<1].cnt + aint[chain][(nod<<1)|1].cnt;
}
void update_heavy (int x, int y){
if (whatChain[x] == whatChain[y]){
int posx = positionInChain[x], posy = positionInChain[y];
if (posx > posy)
swap (posx,posy);
update (whatChain[x],1,1,chains[whatChain[x]].size()-1,posx,posy);
return;
}
if (level[chainFatherNode[whatChain[x]]] <= level[chainFatherNode[whatChain[y]]])
swap (x,y);
update (whatChain[x],1,1,chains[whatChain[x]].size()-1,positionInChain[x],chains[whatChain[x]].size()-1);
int nr = chainFatherNode[whatChain[x]];
update_heavy (nr,y);
}
int main (){
//ifstream cin ("date.in");
//ofstream cout ("date.out");
cin>>n>>q;
for (i=1;i<n;i++){
cin>>x>>y;
L[x].push_back(y);
L[y].push_back(x);
g[x]++, g[y]++;
}
for (i=1;i<=n;i++)
if (g[i] > 1){
rad = i;
break;
}
dfs (rad,0);
for (i=1;i<=nr_chains;i++){
aint[i].resize(chains[i].size()*4);
build (i,1,1,chains[i].size()-1);
}
for (;q--;){
cin>>m;
/// calculez nr de frunze
int nr = f[rad] + m;
w.clear();
for (i=1;i<=m;i++){
cin>>v[i];
if (frunza[v[i]] && !mrk[v[i]]) /// asta nu o sa mai fie frunza
nr--;
mrk[v[i]]++;
w.insert(v[i]);
}
if (nr % 2){
cout<<"-1\n";
for (i=1;i<=m;i++)
mrk[v[i]]--;
continue;
}
for (auto it : w){
if (frunza[it]){
if (mrk[it] % 2 == 0)
update_heavy (it,rad);
} else {
if (mrk[it] % 2)
update_heavy (it,rad);
}
}
/*if (m == 2){
for (i=1;i<=nr_chains;i++)
cout<<aint[i][1].cnt<<" ";
cout<<endl;
}*/
int sol = n + m - 2;
for (i=1;i<=nr_chains;i++) /// o sa mi iau tle pe asta da csf
sol += aint[i][1].cnt;
cout<<sol<<"\n";
/// reintializez vectorul si refac aintul
for (auto it : w){
if (frunza[it]){
if (mrk[it] % 2 == 0)
update_heavy (it,rad);
} else {
if (mrk[it] % 2)
update_heavy (it,rad);
}
}
for (i=1;i<=m;i++)
mrk[v[i]]--;
}
return 0;
}
