foo.cc: In function 'int main()':
foo.cc:27:9: error: 'if\U0000ff08ans' was not declared in this scope
   27 |         if（ans==20||ans==210）
      |         ^~~~~~~
foo.cc:27:27: error: unable to find numeric literal operator 'operator""\U0000ff09'
   27 |         if（ans==20||ans==210）
      |                           ^~~~~
foo.cc:27:27: note: use '-fext-numeric-literals' to enable more built-in suffixes

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