Warning: This contract is very close to the end of storage. This limits its future upgradability.
 --> <stdin>:6:17:
  |
6 | contract C is B layout at 2**256 - 2**40 { uint z; }
  |                 ^^^^^^^^^^^^^^^^^^^^^^^^
Note: There are 0xfffffffffc storage slots between this state variable and the end of storage.
 --> <stdin>:6:44:
  |
6 | contract C is B layout at 2**256 - 2**40 { uint z; }
  |                                            ^^^^^^
