func_code_string: #include <bits/stdc++.h>   using namespace std;   template <typename T>   void display(T a[], int size) {     for (int i = 0; i < size; i++) {       cout << a[i] <<    ;     }     cout << endl;   }   void display(vector<pair<int, int> > a) {     for (int i = 0; i < a.size(); i++) {       cout <<  (  << a[i].first <<  ,  << a[i].second <<  )             <<    ;     }     cout << endl;   }   void display(vector<int> a) {     for (int i = 0; i < a.size(); i++) {       cout << a[i];       if (i == a.size() - 1)         cout << endl;       else         cout <<    ;     }   }   template <typename T>   void initialise(T a[], T value, int length) {     for (int i = 0; i < length; i++) a[i] = value;   }   template <typename T>   void initialise(vector<T>& a, T value) {     for (int i = 0; i < a.size(); i++) a[i] = value;   }   bool compare(pair<int, int> a, pair<int, int> b) {     if (a.first != b.first)       return a.first < b.first;     else       return a.second < b.second;   }   int max(int a[], int n) {     int max = -1000000000;     for (int i = 0; i < n; i++) {       if (a[i] > max) max = a[i];     }     return max;   }   bool find(string a[], string s, int n) {     int left = 0;     int right = n - 1;     while (left < right) {       int mid = (left + right) / 2;       if (s.compare(a[mid]) == 0)         return true;       else if (s.compare(a[mid]) < 0) {         right = mid;       } else {         left = mid + 1;       }     }     return false;   }   void factor(int a[], int base, int num, int n) {     for (int i = n - 1; i >= 0; i--) {       a[i] = num % base;       num = num / base;     }   }   int findLength(int n, int base) {     int i = 0;     while (n > 0) {       i++;       n = n / base;     }     return i;   }   int gcd(int a, int b) {     while (a % b != 0 && b % a != 0) {       if (b > a) {         b = b % a;       } else if (a > b) {         a = a % b;       }     }     if (a <= b)       return a;     else       return b;   }   int main() {     int n, m;     cin >> n >> m;     list<int> son[n];     for (int i = 0; i < m; i++) {       int u, v;       cin >> u >> v;       son[u - 1].push_back(v - 1);       son[v - 1].push_back(u - 1);     }     int side[n];     initialise(side, -1, n);     for (int i = 0; i < n; i++) {       if (side[i] != -1) continue;       queue<int> q;       q.push(i);       side[i] = 0;       while (!q.empty()) {         int current = q.front();         q.pop();         for (auto fil : son[current]) {           if (side[fil] == -1) {             side[fil] = 1 - side[current];             q.push(fil);           } else if (side[fil] == side[current]) {             cout << -1 << endl;             return 0;           } else             continue;         }       }     }     vector<int> zero;     vector<int> one;     for (int i = 0; i < n; i++) {       if (side[i] == 0)         zero.push_back(i + 1);       else         one.push_back(i + 1);     }     cout << zero.size() << endl;     for (int i = 0; i < zero.size(); i++) {       cout << zero[i];       if (i == zero.size() - 1)         cout << endl;       else         cout <<    ;     }     cout << one.size() << endl;     for (int i = 0; i < one.size(); i++) {       cout << one[i];       if (i == one.size() - 1)         cout << endl;       else         cout <<    ;     }     return 0;   }   