func_code_string: #include <bits/stdc++.h>   using namespace std;   pair<int, int> add(pair<int, int> p1, pair<int, int> p2, int odd, int even) {     return make_pair(p1.first + p2.first - odd, p1.second + p2.second - even);   }   pair<int, int> dfs(vector<int>* adj, int* visited, int* store, int u,                      int parent, int odd, int even, int* l, int* m,                      vector<int>& v) {     visited[u] = 1;     int level = store[u];     if (level % 2 == 1) {       if (l[u] != m[u] ^ odd % 2 == 1) {         odd++;         v.push_back(u);       }     } else {       if (l[u] != m[u] ^ even % 2 == 1) {         even++;         v.push_back(u);       }     }     pair<int, int> p = make_pair(odd, even);     int a = p.first, b = p.second;     for (int i = 0; i < adj[u].size(); i++) {       if (adj[u][i] != parent && !visited[adj[u][i]])         p = add(p, dfs(adj, visited, store, adj[u][i], u, a, b, l, m, v), a, b);     }     return p;   }   int main() {     int n;     scanf( %d , &n);     ;     vector<int>* adj = new vector<int>[n];     for (int i = 0; i < n - 1; i++) {       int a, b;       scanf( %d , &a);       ;       scanf( %d , &b);       ;       a--;       b--;       adj[a].push_back(b);       adj[b].push_back(a);     }     int l[n], m[n];     for (int i = 0; i < n; i++) scanf( %d , &l[i]);     ;     for (int i = 0; i < n; i++) scanf( %d , &m[i]);     ;     int* visited = (int*)calloc(n, sizeof(int));     int* store = (int*)calloc(n, sizeof(int));     queue<int> q;     int even = 0, odd = 0, level = 1;     q.push(0);     q.push(-1);     visited[0] = 1;     while (!q.empty()) {       int u = q.front();       q.pop();       if (u == -1 && !q.empty()) {         level++;         q.push(-1);         continue;       } else if (u == -1)         break;       visited[u] = 1;       store[u] = level;       for (int i = 0; i < adj[u].size(); i++) {         if (!visited[adj[u][i]]) {           q.push(adj[u][i]);           visited[adj[u][i]] = 1;         }       }     }     for (int i = 0; i < n; i++) visited[i] = 0;     vector<int> v;     pair<int, int> p = dfs(adj, visited, store, 0, -1, 0, 0, l, m, v);     cout << p.first + p.second << endl;     for (int i = 0; i < v.size(); i++) cout << v[i] + 1 << endl;     return 0;   }   