Traceback (most recent call last):
  File "/usr/lib/python3.8/py_compile.py", line 144, in compile
    code = loader.source_to_code(source_bytes, dfile or file,
  File "<frozen importlib._bootstrap_external>", line 911, in source_to_code
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/w/foo.py", line 3
    using namespace std;
          ^
SyntaxError: invalid syntax

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/lib/python3.8/py_compile.py", line 150, in compile
    raise py_exc
py_compile.PyCompileError:   File "/w/foo.py", line 3
    using namespace std;
          ^
SyntaxError: invalid syntax

[Hydro](https://hydro.ac)提供评测服务