Friends Meetup

Chef and his friend is standing on the X-axis at the points $X_1$ and $X_2$ respectively. Chef moves one step forward each second (that is he moves to $X_1 + 1$ after the $1^{st}$ second, $X_1 + 2$ after the $2^{nd}$ second, and so on), whereas his friend moves $2$ steps forward each second (that is he moves to $X_2 + 2$ after the $1^{st}$ second, $X_2 + 4$ after the $2^{nd}$ second, and so on).