View Compilation Error

0_0_39586490_11538.cpp: In function 'void dfs(int)':
0_0_39586490_11538.cpp:15:25: error: 'dfs_clock' was not declared in this scope
   15 |     pre[u] = low[u] = ++dfs_clock;
      |                         ^~~~~~~~~
0_0_39586490_11538.cpp: In function 'int main()':
0_0_39586490_11538.cpp:78:22: error: 'cnum' was not declared in this scope; did you mean 'num'?
   78 |         if (ans > 1) cnum << 0 << endl;
      |                      ^~~~
      |                      num
0_0_39586490_11538.cpp:84:13: error: 'cnum' was not declared in this scope; did you mean 'num'?
   84 |             cnum << sum << endl;
      |             ^~~~
      |             num