Recoiling board

Classical Mechanics Level 1

Sam is standing at one end of a $\SI{10}{\meter}$ board on an ice floor. The board’s mass is $\SI{30}{\kilo\gram}$ and Sam weighs $\SI{50}{\kilo\gram}.$

What distance, with respect to the ice on the ground, does Sam travel if he walks to the other end of the board?

Assumptions: for simplicity, assume that there is no friction between the ice and the board.