func_code_string: #include <bits/stdc++.h>   using namespace std;   int a, b, n, i, p[1001], sz[1001], cnt[1001];   vector<pair<int, int> > v2;   vector<int> v;   int find_p(int a) {     if (p[a] == a) return a;     return p[a] = find_p(p[a]);   }   void unionn(int a, int b) {     int _a = a, _b = b;     a = find_p(a);     b = find_p(b);     if (a != b) {       if (sz[a] < sz[b]) swap(a, b);       p[b] = a;       sz[a] += sz[b];     } else       v2.push_back({_a, _b});   }   int main() {     cin >> n;     for (i = 1; i <= n; i++) p[i] = i, sz[i] = 1;     for (i = 1; i < n; i++) {       cin >> a >> b;       unionn(a, b);     }     cout << v2.size() << endl;     for (i = 1; i <= n; i++) {       p[i] = find_p(i);       if (!cnt[p[i]]) {         v.push_back(p[i]);         cnt[p[i]] = 1;       }     }     for (i = 0; i < v2.size(); i++) {       cout << v2[i].first <<     << v2[i].second <<     << v[i] <<     << v[i + 1]            << endl;     }   }   