#include<bits/stdc++.h>
using namespace std;
#define int long long
#define inf (int)2e18
#define nl '\n'
const int N = 1e5+1;
vector<int> g[N], gvt[N];
int dp[N], odd[N], eve[N], dep[N], up[N][18], tin[N], sz[N];
int ans, fans, cnt;
void dfs(int v, int p){
tin[v] = cnt++;
if(g[v].size() == 1) dp[v] = 1;
for(int ch : g[v]){
if(ch == p) continue;
dep[ch] = dep[v] + 1;
up[ch][0] = v;
dfs(ch, v);
dp[v] += dp[ch];
if(dp[ch] % 2 == 0) ans++;
}
}
void dfs2(int v, int p){
odd[v] = odd[p];
eve[v] = eve[p];
(dp[v] % 2 ? odd[v] : eve[v])++;
for(int ch : g[v]){
if(ch != p) dfs2(ch, v);
}
}
void dfs3(int v){
for(int ch : gvt[v]){
dfs3(ch);
sz[v] += sz[ch];
if(sz[ch] % 2) fans += odd[ch] - odd[v] - (eve[ch] - eve[v]);
}
}
int lca(int x, int y){
if(dep[x] > dep[y]) swap(x, y);
int k = dep[y] - dep[x];
for(int i = 0; i < 18; i++) if(k & 1<<i) y = up[y][i];
if(x == y) return x;
for(int i = 17; i >= 0; i--){
if(up[x][i] == up[y][i]) continue;
x = up[x][i];
y = up[y][i];
}
return up[x][0];
}
bool cmp(int x, int y){
return tin[x] < tin[y];
}
void solve(){
int n, q;
cin>>n>>q;
for(int i = 1; i < n; i++){
int x, y;
cin>>x>>y;
g[x].push_back(y);
g[y].push_back(x);
}
int r, tot = 0;
for(int i = 1; i <= n; i++){
if(g[i].size() > 1) r = i;
else tot++;
}
r = 2;
up[r][0] = r;
dfs(r, 0);
dfs2(r, 0);
for(int j = 1; j < 18; j++){
for(int i = 1; i <= n; i++){
up[i][j] = up[up[i][j-1]][j-1];
}
}
while(q--){
int m;
cin>>m;
vector<int> v(m);
for(int &x : v) cin>>x;
auto l = v;
sort(v.begin(), v.end(), cmp);
for(int i = 1; i < m; i++){
v.push_back(lca(v[i-1], v[i]));
}
sort(v.begin(), v.end(), cmp);
v.erase(unique(v.begin(), v.end()), v.end());
for(int x : v){
sz[x] = (g[x].size() == 1 ? -1 : 0);
gvt[x].clear();
}
for(int x : l) sz[x]++;
for(int i = 1; i < m; i++){
gvt[lca(v[i-1], v[i])].push_back(v[i]);
}
fans = ans + n + m - 1;
r = v[0];
dfs3(r);
cout<<((tot + sz[r]) % 2 == 0 ? fans : -1)<<nl;
}
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);cout.tie(NULL);
int t = 1;
//cin>>t;
while(t--) solve();
return 0;
}
