func_code_string: #include <bits/stdc++.h>   using namespace std;   int l[10100];   int r[10100];   int per[100100];   int pr(int x) {     if (x == per[x]) return x;     return per[x] = pr(per[x]);   }   int main() {     ios::sync_with_stdio(0);     int n;     cin >> n;     int t = 0;     for (int i = 1; i <= n; i++) {       per[i] = i;       cin >> l[i];       cin >> r[i];       t += l[i] == 0;     }     for (int i = 1; i <= n; i++) {       if (l[i]) {         r[l[i]] = i;         per[pr(i)] = pr(l[i]);       }       if (r[i]) {         l[r[i]] = i;         per[pr(i)] = pr(r[i]);       }     }     for (int i = 1; i <= n; i++) {       if (l[i] == 0) {         if (t == 1) continue;         for (int j = 1; j <= n; j++) {           if (i == j) continue;           if (pr(i) == pr(j)) continue;           if (r[j] == 0) {             r[j] = i;             l[i] = j;             per[pr(i)] = pr(j);             break;           }         }         t--;       }     }     for (int i = 1; i <= n; i++) {       cout << l[i] <<     << r[i] <<   n ;     }     return 0;   }   