#include <bits/stdc++.h>
using namespace std;
#define int long long
const int modulo = 1e9+7;
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int N,Q;
cin >> N >> Q;
vector<vector<int>> adj(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;
{
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++;}
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;
}
}
auto flip = [&](int x){
while(x){
status[x]^=1;
if(status[x])cntEven--;
else cntEven++;
x = par[x];
}
};
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);
}
}
}
