foo.cc: In function 'int main()':
foo.cc:7:7: error: unable to find numeric literal operator 'operator""\U0000ff1b'
    7 | cout<<123；
      |       ^~~~~
foo.cc:7:7: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:13:6: error: expected ';' before numeric constant
   13 | }cout 6 <<sum<<endl;
      |      ^~
      |      ;
foo.cc:13:2: warning: statement has no effect [-Wunused-value]
   13 | }cout 6 <<sum<<endl;
      |  ^~~~

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