Driver code
let a = [ [ 2 , 9 , 1 , 4 , - 2 ] , [ 6 , 7 , 2 , 11 , 4 ] , [ 4 , 2 , 9 , 2 , 4 ] , [ 1 , 9 , 2 , 4 , 4 ] , [ 0 , 2 , 4 , 2 , 5 ] ] ; document . write ( HalfDiagonalSums ( a , 5 ) ? " " : " " ) ;