class MAIN is

  ackermann(m, n:INT):INT
    pre m >= 0 and n >= 0
  is
    if m = 0 then return n + 1; end;
    if n = 0 then return ackermann(m-1, 1); end;
    return ackermann(m-1, ackermann(m, n-1));
  end;

  main is
    n, m :INT;
    loop n := 0.upto!(6);
      loop m := 0.upto!(3);
        #OUT + "A(" + m + ", " + n + ") = " + ackermann(m, n) + "\n";
      end;
    end;
  end;
end;