foo.cc: In function 'int bfs()':
foo.cc:46:15: error: unable to find numeric literal operator 'operator""\U0000ff1b'
   46 |        return 0；
      |               ^~~
foo.cc:46:15: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:46:18: error: expected ';' before '}' token
   46 |        return 0；
      |                  ^
      |                  ;
   47 | }
      | ~                 

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