A zombie moves along a 1 dimensional line. It starts at position x, and at each time step, it moves y steps to the right. x and y are integers unknown to you. (If y is negative, it means the zombie moves -y steps to the left.) After each time step, you are allowed to examine any integer position and ask if the zombie is in that position. If correct, you get to shoot the zombie on the head and the zombie will be eliminated. Devise an algorithm that is guaranteed to kill the zombie.