Warning: 'transfer' is deprecated and scheduled for removal. Use 'call{value: <amount>}("")' instead.
  --> input.sol:10:3:
   |
10 | 		a.transfer(x);
   | 		^^^^^^^^^^

Warning: BMC: Underflow (resulting value less than 0) happens here.
 --> input.sol:7:3:
  |
7 | 		--x;
  | 		^^^
Note: Counterexample:
  <result> = (- 1)
  a = 0
  x = 0

Note: Callstack:
Note:
