initialising tree
v [ 1 ] . Add ( new Tuple < int , int > ( 4 , 4 ) ) ; v [ 4 ] . Add ( new Tuple < int , int > ( 1 , 4 ) ) ; v [ 1 ] . Add ( new Tuple < int , int > ( 2 , 2 ) ) ; v [ 2 ] . Add ( new Tuple < int , int > ( 1 , 2 ) ) ; v [ 2 ] . Add ( new Tuple < int , int > ( 3 , 3 ) ) ; v [ 3 ] . Add ( new Tuple < int , int > ( 2 , 3 ) ) ; v [ 2 ] . Add ( new Tuple < int , int > ( 5 , 5 ) ) ; v [ 5 ] . Add ( new Tuple < int , int > ( 2 , 5 ) ) ;