0 pragma solidity ^0.5.0;

1 contract Vulnerable4Calls {

2

3 address public owner;

4 bool locked;

5 uint256 public maybePrime = 973013;

6

7 modifier onlyOwner {

8 require(msg.sender == owner);

9 _;

10 }

11

12 modifier only_uninitialized {

13 require(owner == address(0));

14 _;

15 }

16

17 constructor() public {

18 _init(msg.sender);

19 locked = true;

20 }

21

22 function _init(address _owner) public only_uninitialized {

23 owner = _owner;

24 }

25

26 function reset() public {

27 owner = address(0);

28 }

29

30 function unlock(uint256 x, uint256 y) public {

31 require(x > 1 && x < maybePrime);

32 require(y > 1 && y < maybePrime);

33 require(x*y != maybePrime);

34

35 locked = false;

36 }

37

38 function kill() public onlyOwner {

39 require(!locked);

40 selfdestruct(msg.sender);

41 }

42 }