#include<bits/stdc++.h> #define debug(x) cerr << #x << " " << x << "\n" #define debugs(x) cerr << #x << " " << x << " " #pragma GCC optimize("Ofast") #define int long long using namespace std; mt19937 rng(chrono::steady_clock::now().time_since_epoch().count()); int range_rng(int l, int r) { return uniform_int_distribution<int>(l,r)(rng); } priority_queue<int> pqmax[200005]; priority_queue<int> pqmin[200005]; vector<int> nodes[200005]; int h[200005]; int u[200005]; int leaves[200005]; int ans; bool ok; void dfs(int node, int parent) { leaves[node]=0; if (nodes[node].size()==1 && parent!=-1) { leaves[node]=1; pqmax[node].push(h[node]); pqmin[node].push(-h[node]); return; } int min1,min2,sum; min1=1e9; min2=1e9; sum=0; for (auto x : nodes[node]) { if (x!=parent) { h[x]=h[node]+1; dfs(x,node); leaves[node]+=leaves[x]; while (!pqmax[x].empty()) { sum+=pqmax[x].top(); pqmax[x].pop(); } if (-pqmin[x].top()<min1) { min2=min1; min1=-pqmin[x].top(); } else if (-pqmin[x].top()<min2) { min2=-pqmin[x].top(); } while (!pqmin[x].empty()) { pqmin[x].pop(); } } } if (parent!=-1) { if (leaves[node]%2==0) { ans+=(sum-min1-min2)-(h[node]*(leaves[node]-2)); pqmin[node].push(-min1); pqmin[node].push(-min2); pqmax[node].push(min1); pqmax[node].push(min2); leaves[node]=2; } else { ans+=(sum-min1)-(h[node]*(leaves[node]-1)); pqmin[node].push(-min1); pqmax[node].push(min1); leaves[node]=1; } } else { if (leaves[node]%2==0) ans+=sum-h[node]*leaves[node]; else ok=false; leaves[node]=0; } } signed main() { /* ifstream fin("arbore.in"); ofstream fout("arbore.out"); */ ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); int n,q,i,j,uu,v,root,d; cin >> n >> q; for (i=1; i<=n-1; i++) { cin >> uu >> v; nodes[uu].push_back(v); nodes[v].push_back(uu); } for (i=1; i<=n; i++) { if (nodes[i].size()!=1) { root=i; break; } } for (i=1;i<=q;i++) { cin >> d; for (j=1;j<=d;j++) { cin >> u[j]; nodes[u[j]].push_back(n+j); nodes[n+j].push_back(u[j]); } h[root]=0; ok=true; ans=0; dfs(root,-1); if (ok) cout << ans << "\n"; else cout << "-1\n"; for (j=1;j<=d;j++) { nodes[u[j]].pop_back(); nodes[n+j].pop_back(); } } return 0; }