func_code_string: #include <bits/stdc++.h>   using namespace std;   template <typename T>   inline T read() {     T x = 0, f = 1;     char ch = getchar();     while (ch <  0  || ch >  9 ) {       if (ch ==  - ) f = -1;       ch = getchar();     }     while (ch >=  0  && ch <=  9 ) {       x = (x << 1) + (x << 3) + (ch ^ 48);       ch = getchar();     }     return x * f;   }   const int N = 100010, INF = 0x3f3f3f3f;   int n, q, k, key[N];   struct Edge {     int to, nxt;   };   struct Graph {     int head[N], tot;     Edge e[N << 1];     void addedge(int x, int y) {       e[++tot] = (Edge){y, head[x]};       head[x] = tot;     }   };   struct Tree : public Graph {     int dfn[N], ti, f[N][19], dep[N];     void dfs(int x, int fa) {       dfn[x] = ++ti;       f[x][0] = fa;       dep[x] = dep[fa] + 1;       for (int i = 1; i <= 18; i++) f[x][i] = f[f[x][i - 1]][i - 1];       for (int i = head[x]; i; i = e[i].nxt) {         int y = e[i].to;         if (y == fa) continue;         dfs(y, x);       }     }     int lca(int x, int y) {       if (dep[x] < dep[y]) swap(x, y);       for (int i = 18; i >= 0; i--) {         if (dep[f[x][i]] >= dep[y]) x = f[x][i];       }       if (x == y) return x;       for (int i = 18; i >= 0; i--) {         if (f[x][i] != f[y][i]) x = f[x][i], y = f[y][i];       }       return f[x][0];     }   } t;   struct Virtual_Tree : public Graph {     int dp[N][2], d[N], st[N], tp;     void build_vtree(Tree& t, int* key, int cnt) {       memcpy(d, key, sizeof(int) * (cnt + 1));       sort(d + 1, d + cnt + 1, [&](int x, int y) { return t.dfn[x] < t.dfn[y]; });       head[1] = 0, tot = 0;       st[tp = 1] = 1;       for (int i = 1; i <= cnt; i++) {         if (d[i] == 1) continue;         int lc = t.lca(d[i], st[tp]);         if (lc != st[tp]) {           while (t.dfn[lc] < t.dfn[st[tp - 1]]) {             addedge(st[tp - 1], st[tp]);             tp--;           }           if (t.dfn[lc] != t.dfn[st[tp - 1]]) {             head[lc] = 0, addedge(lc, st[tp]);             st[tp] = lc;           } else             addedge(lc, st[tp]), tp--;         }         head[d[i]] = 0, st[++tp] = d[i];       }       for (int i = 1; i < tp; i++) addedge(st[i], st[i + 1]);     }     void dfs_dp(int, int);   } vt;   int iskey[N];   void Virtual_Tree::dfs_dp(int x, int fa) {     dp[x][0] = (!iskey[x]) * n, dp[x][1] = iskey[x] * n;     int minx = INF, sum = 1, cnt = 0;     for (int i = head[x]; i; i = e[i].nxt) {       int y = e[i].to;       if (y == fa) continue;       cnt += iskey[y];       dfs_dp(y, x);       if (iskey[x])         dp[x][0] += min(dp[y][1], dp[y][0] + 1);       else {         minx = min(minx, dp[y][0] - dp[y][1]);         sum += min(dp[y][0], dp[y][1]);         dp[x][1] += dp[y][1];       }     }     if (!iskey[x] && cnt <= 1) dp[x][0] = dp[x][1] + minx;     if (!iskey[x]) dp[x][1] = min(dp[x][1], sum);   }   void solve() {     k = read<int>();     for (int i = 1; i <= k; i++) iskey[key[i] = read<int>()] = 1;     for (int i = 1; i <= k; i++) {       int x = key[i];       if (iskey[t.f[x][0]]) {         for (int j = 1; j <= k; j++) iskey[key[j]] = 0;         puts( -1 );         return;       }     }     vt.build_vtree(t, key, k);     vt.dfs_dp(1, 0);     printf( %d n , min(vt.dp[1][0], vt.dp[1][1]));     for (int j = 1; j <= k; j++) iskey[key[j]] = 0;   }   int main() {     n = read<int>();     for (int i = 1; i < n; i++) {       int x = read<int>(), y = read<int>();       t.addedge(x, y);       t.addedge(y, x);     }     t.dfs(1, 0);     q = read<int>();     while (q--) solve();     return 0;   }   