#include <bits/stdc++.h>
using namespace std;
#define int long long
const int modulo = 1e9+7;
struct segtree{
vector<int> tree,lazy;
int N;
segtree(int N):tree(8*N),lazy(9*N),N(N){}
int sum(int L,int R,int x,int QL,int QR){
int mid = (L+R)/2;
if(lazy[x]){
lazy[x]=0;
tree[x] = R-L+1-tree[x];
lazy[2*x]^=1;
lazy[2*x+1]^=1;
}
if(QL<=L and R<=QR)return tree[x];
if(R<QL or QR<L)return 0;
return sum(L,mid,2*x,QL,QR)+sum(mid+1,R,2*x+1,QL,QR);
}
int sum(int x){
return sum(1,N,1,1,x);
}
void flipUpdate(int L,int R,int x,int QL,int QR){
int mid = (L+R)/2;
if(lazy[x]){
lazy[x]=0;
tree[x] = R-L+1-tree[x];
lazy[2*x]^=1;
lazy[2*x+1]^=1;
}
if(R<QL or QR<L)return;
if(QL<=L and R<=QR){
tree[x] = R-L+1-tree[x];
lazy[2*x]^=1;
lazy[2*x+1]^=1;
return;
}
flipUpdate(L,mid,2*x,QL,QR);
flipUpdate(mid+1,R,2*x+1,QL,QR);
tree[x]=tree[2*x]+tree[2*x+1];
}
void flipUpdate(int L,int R){
flipUpdate(1,N,1,L,R);
}
};
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int N,Q;
cin >> N >> Q;
vector<vector<int>> adj(N+1);
vector<vector<int>> newAdj(N+1);
for(int i=1;i<N;i++){
int u,v;cin>>u>>v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
vector<int> par(N+1);
vector<int> status(N+1);
vector<bool> isLeaf(N+1);
int cntEven = 0;
int root = 0;
segtree bit(N);
{
function<int(int,int)> dfs = [&](int x,int p){
int curr = 0;
int children = 0;
par[x]=p;
for(int&i:adj[x])if(i!=p){curr^=dfs(i,x);children++;newAdj[x].emplace_back(i);}
if(children==0){curr=1;isLeaf[x]=true;}
if(curr==0)cntEven++;
status[x]=curr;
return curr;
};
for(int i=1;i<=N;i++)if(adj[i].size()>1){
dfs(i,0);
root = i;
break;
}
}
swap(adj,newAdj);
{
vector<int> subsize(N+1);
function<int(int)> dfs = [&](int x){
subsize[x]=1;
for(int&i:adj[x]){
auto t = dfs(i);
subsize[x]+=t;
if(t>subsize[adj[x][0]])swap(adj[x][0],i);
}
return subsize[x];
};
assert(dfs(root)==N);
}
vector<int> head(N+1);
vector<int> idx(N+1);
{
int c = 0;
function<void(int)> dfs = [&](int x){
idx[x]=++c;
if(status[x])bit.flipUpdate(idx[x],idx[x]);
for(int&i:adj[x]){
if(i==adj[x][0])head[i]=head[x];
else head[i]=i;
dfs(i);
}
};
head[root]=root;
dfs(root);
}
auto flip = [&](int x){
while(x){
int a = idx[head[x]];
int b = idx[x];
bit.flipUpdate(a,b);
x = par[head[x]];
}
status[root] = bit.sum(1);
cntEven = N-bit.sum(N);
};
vector<bool> isModified(N+1);
for(int i=1;i<=Q;i++){
int D;cin>>D;
vector<int> updates(D);
for(int&x:updates){
cin >> x;
if(isLeaf[x] and !isModified[x])isModified[x]=true;
else flip(x);
}
if(status[root]==0)cout << cntEven+N+D-2 << '\n';
else cout << "-1\n";
for(int&x:updates){
if(isLeaf[x] and isModified[x])isModified[x]=false;
else flip(x);
}
}
}
