The following information is available from a company's Cash Flow Statement for the month of May 2020: the Cash Used For Investing Activities was minus 18 thousand dollars, Cash Derived From Financing Activities was minus 5 thousand dollars, and the Cash Derived From Operating Activities was plus 31 thousand dollars. If the Balance Sheet for the end of May 2020 shows Net Cash of plus 22 thousand dollars, what was Net Cash on the balance sheet at the end of April 2020, expressed in thousands of dollars?