View Compilation Error

0_0_39049591_6840.cpp: In function 'int main()':
0_0_39049591_6840.cpp:24:19: error: unable to find numeric literal operator 'operator""n'
   24 |         cout<<sum-2n;
      |                   ^~
0_0_39049591_6840.cpp:24:19: note: use '-fext-numeric-literals' to enable more built-in suffixes