PACKAGE Useful IS

-- useful subtypes
SUBTYPE ZeroToEight IS integer RANGE 0..8;
SUBTYPE OneToEight IS integer RANGE 1..8;

-- useful arrays
TYPE columns IS ARRAY (1..8) OF OneToEight;
TYPE ColumnFree IS ARRAY (1..8) OF Boolean;
TYPE UpFree IS ARRAY (2..16) OF Boolean;
TYPE DownFree IS ARRAY (-7..7) OF Boolean;

-- useful variable
Row : ZeroToEight;     -- limit number of rows on board
Count : integer := 0;  -- counter for solutions

END useful;