Stores the X and Y coordinates
List < int > X = new List < int > ( ) ; List < int > Y = new List < int > ( ) ; for ( int i = 0 ; i < N ; i ++ ) { X . Add ( x1 [ i ] ) ; X . Add ( x2 [ i ] - 1 ) ; Y . Add ( y1 [ i ] ) ; Y . Add ( y2 [ i ] - 1 ) ; }