func_code_string: #include <bits/stdc++.h>   using namespace std;   const int c = 200002;   int sum, n, ans[c], pos;   vector<int> sz[c];   bool v[c];   bool dfs(int a) {     v[a] = true;     int el = a;     for (int i = 0; i < sz[a].size(); i++) {       int x = sz[a][i];       if (!v[x] && !dfs(x)) ans[el] = x, el = x;     }     if (el != a) {       ans[el] = a, sum -= 2;       return 1;     }     return 0;   }   int main() {     cin >> n, sum = 2 * n;     for (int i = 1; i < n; i++) {       int x, y;       cin >> x >> y;       sz[x].push_back(y), sz[y].push_back(x);     }     for (int i = 1; i <= n; i++)       if (sz[i].size() == 1) pos = sz[i][0];     dfs(pos);     cout << sum <<   n ;     for (int i = 1; i <= n; i++) cout << ans[i] <<    ;     return 0;   }   