foo.cc: In function 'int depth(int)':
foo.cc:9:10: error: 'pow' was not declared in this scope
    9 |   sum += pow(2, j);
      |          ^~~
foo.cc: In function 'int main()':
foo.cc:36:22: error: 'pow' was not declared in this scope; did you mean 'pos'?
   36 |   for (int j = 0;j < pow(2, i - 1);j++)
      |                      ^~~
      |                      pos

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