foo.cc:9:1: error: 'vector' does not name a type
    9 | vector<int> result;
      | ^~~~~~
foo.cc:13:33: error: 'vector' has not been declared
   13 | void dfs(int u, int n, ULL sum, vector<int> res)
      |                                 ^~~~~~
foo.cc:13:39: error: expected ',' or '...' before '<' token
   13 | void dfs(int u, int n, ULL sum, vector<int> res)
      |                                       ^
foo.cc: In function 'void dfs(int, int, ULL, int)':
foo.cc:22:13: error: 'result' was not declared in this scope
   22 |             result = res;
      |             ^~~~~~
foo.cc:22:22: error: 'res' was not declared in this scope
   22 |             result = res;
      |                      ^~~
foo.cc:31:17: error: 'res' was not declared in this scope
   31 |                 res.push_back(i - 1);
      |                 ^~~
foo.cc:37:17: error: 'res' was not declared in this scope
   37 |                 res.push_back(n / i - 1);
      |                 ^~~
foo.cc: In function 'int main()':
foo.cc:54:29: error: 'result' was not declared in this scope
   54 |         for (int i = 0; i < result.size(); i ++ )
      |                             ^~~~~~

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