func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, ai, bi;   vector<vector<int> > adj(200009);   vector<int> vis(200009, 0);   vector<pair<int, int> > se;   void dfs(int v, int vl) {     if (vis[v]) return;     vis[v] = vl;     vl = (vl == 1) ? 2 : 1;     int len = adj[v].size();     for (int i = 0; i < len; i++) dfs(adj[v][i], vl);   }   int main() {     cin >> n;     for (int i = 0; i < n; i++) {       cin >> ai >> bi;       se.push_back(make_pair(ai, bi));       adj[ai].push_back(bi);       adj[bi].push_back(ai);       adj[(2 * i)].push_back(2 * i + 1);       adj[(2 * i + 1)].push_back(2 * i);     }     for (int i = 1; i <= 2 * n; i++)       if (!vis[i]) dfs(i, 1);     for (int i = 0; i < n; i++)       cout << vis[se[i].first] <<     << vis[se[i].second] <<   n ;   }   