View Compilation Error

0_0_22281883_16031.cpp: In function 'void dfs_root(int, int)':
0_0_22281883_16031.cpp:22:28: error: 'f' was not declared in this scope
     maxv[u] = max(maxv[u], f[0] - maxv[u]);
                            ^
0_0_22281883_16031.cpp:29:24: error: 'rt' was not declared in this scope
         dfs_root(v, u, rt);
                        ^
0_0_22281883_16031.cpp: In function 'void DFS(int)':
0_0_22281883_16031.cpp:68:30: error: too many arguments to function 'void dfs_root(int, int)'
         dfs_root(v, root=0, v);
                              ^
0_0_22281883_16031.cpp:20:6: note: declared here
 void dfs_root(int u, int fa)
      ^