func_code_string: #include <bits/stdc++.h>   using namespace std;   map<long long int, vector<long long int>> v;   map<long long int, long long int> vis;   void dfs(long long int n) {     long long int i;     cout << n <<    ;     vis[n] = 1;     for (i = 0; i < v[n].size(); i++) {       if (!vis[v[n][i]]) {         vis[v[n][i]] = 1;         dfs(v[n][i]);       }     }   }   int main() {     long long int n, i, j, k, p, q, ans = 0;     cin >> n;     map<long long int, long long int> make_pair;     for (i = 1; i <= n; i++) {       cin >> p >> q;       v[p].push_back(q);       v[q].push_back(p);       make_pair[p]++;       make_pair[q]++;     }     for (auto it : make_pair) {       if (it.second == 1) {         ans = it.first;         break;       }     }     dfs(ans);   }   