A queen q$1$ is said to attack another queen q$2,$ if q$2$ is in the same row as q$1,$ or

in the same column as q$1,$ or in a square which is diagonal to the square occupied by q$1.$

For example: In the above figure, if there is a Queen in position $1$A as shown it will

attack all the squares marked with an X$,$ Thus there cannot be any other queen in any of

these squares.