Sections 15-3-15 and 15-3-16 shall not extend to lands or tenements to which there is an adverse title, the holder of which is, at the expiration of said ten years, under the age of twenty-one years, mentally ill, or imprisoned for a criminal offense for a term less than life; provided, such person shall within three years after the removal of such disability begin an action to recover possession of such lands, or to establish his title thereto, and prosecute the same to judgment with due diligence.
SDCL 15-3-18