func_code_string: #include <bits/stdc++.h>   #pragma GCC target( avx2 )   #pragma GCC optimization( O3 )   #pragma GCC optimization( unroll-loops )   using namespace std;   using ll = long long;   using vll = int64_t;   const int N = 1e6 + 1;   vector<int> adj[N];   vector<bool> vis(N, false);   vector<short> col(N, -1);   inline bool bfs(int src) {     queue<pair<int, int>> q;     q.push({src, 0});     vis[src] = true;     col[src] = 0;     while (!q.empty()) {       auto p = q.front();       q.pop();       for (int i : adj[p.first]) {         if (vis[i]) {           if (col[i] == col[p.first]) {             return false;           }           continue;         }         vis[i] = true;         col[i] = (p.second == 1 ? 0 : 1);         q.push({i, col[i]});       }     }     return true;   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int n;     cin >> n;     int m;     cin >> m;     unordered_set<int> hs;     for (int i = 0; i < m; i++) {       int a, b;       cin >> a >> b;       a--;       b--;       adj[a].push_back(b);       adj[b].push_back(a);       hs.insert(a);       hs.insert(b);     }     for (int i = 0; i < n; i++) {       if (!vis[i] && hs.find(i) != hs.end()) {         bool ok = bfs(i);         if (!ok) {           cout <<  -1 n ;           return 0;         }       }     }     int red = 0, black = 0;     for (int i = 0; i < n; i++) {       if (col[i] == 1)         black++;       else if (col[i] == 0)         red++;     }     cout << red <<   n ;     for (int i = 0; i < n; i++) {       if (col[i] == 0) cout << 1 + i <<    ;     }     cout <<   n ;     cout << black <<   n ;     for (int i = 0; i < n; i++) {       if (col[i] == 1) cout << i + 1 <<    ;     }     return 0;   }   