foo.cc: In function ‘int main()’:
foo.cc:10:18: error: invalid types ‘int[int]’ for array subscript
   10 |                 b[a%3]++;
      |                  ^
foo.cc:12:16: error: invalid types ‘int[int]’ for array subscript
   12 |         cout<<b[0]/2+min(b[1],b[2]);
      |                ^
foo.cc:12:27: error: invalid types ‘int[int]’ for array subscript
   12 |         cout<<b[0]/2+min(b[1],b[2]);
      |                           ^
foo.cc:12:32: error: invalid types ‘int[int]’ for array subscript
   12 |         cout<<b[0]/2+min(b[1],b[2]);
      |                                ^