func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int read() {     char c = getchar();     int x = 0;     bool f = 0;     for (; !isdigit(c); c = getchar()) f ^= !(c ^ 45);     for (; isdigit(c); c = getchar()) x = (x << 1) + (x << 3) + (c ^ 48);     if (f) x = -x;     return x;   }   int n, m, k, s;   vector<int> e[200005];   vector<int> dfn, res[200005];   bool vis[200005];   void dfs(int u) {     vis[u] = 1;     dfn.push_back(u);     for (auto v : e[u])       if (!vis[v]) dfs(v), dfn.push_back(u);   }   signed main() {     n = read(), m = read(), k = read(), s = ceil(2.0 * n / k);     for (register int i = (1); i <= (m); ++i) {       int u = read(), v = read();       e[u].push_back(v), e[v].push_back(u);     }     dfs(1);     for (register int i = (0); i <= ((int)dfn.size() - 1); ++i)       res[i / s + 1].push_back(dfn[i]);     for (register int i = (1); i <= (k); ++i) {       if (!res[i].size()) res[i].push_back(1);       cout << res[i].size() <<    ;       for (auto x : res[i]) cout << x <<    ;       puts(  );     }     return 0;   }   