foo.cc: In function ‘int main()’:
foo.cc:18:22: error: unable to find numeric literal operator ‘operator""）’
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |                      ^~~
foo.cc:18:22: note: use ‘-fext-numeric-literals’ to enable more built-in suffixes
foo.cc:18:27: error: ‘（m’ was not declared in this scope
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |                           ^~~
foo.cc:18:32: error: unable to find numeric literal operator ‘operator""）’
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |                                ^~~
foo.cc:18:32: note: use ‘-fext-numeric-literals’ to enable more built-in suffixes
foo.cc:18:42: error: unable to find numeric literal operator ‘operator""）’
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |                                          ^~~
foo.cc:18:42: note: use ‘-fext-numeric-literals’ to enable more built-in suffixes
foo.cc:18:52: error: unable to find numeric literal operator ‘operator""）’
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |                                                    ^~~~
foo.cc:18:52: note: use ‘-fext-numeric-literals’ to enable more built-in suffixes
foo.cc:18:14: error: ‘if（’ was not declared in this scope
   18 |         else if（(m==4）||（m==6）||（m==9）||（m==11）)
      |              ^~~~
foo.cc:22:9: error: ‘else’ without a previous ‘if’
   22 |         else
      |         ^~~~