create undirected edges
adj [ 1 ] . push_back ( 2 ) ; adj [ 2 ] . push_back ( 1 ) ; adj [ 1 ] . push_back ( 3 ) ; adj [ 3 ] . push_back ( 1 ) ; adj [ 2 ] . push_back ( 4 ) ; adj [ 4 ] . push_back ( 2 ) ; adj [ 2 ] . push_back ( 5 ) ; adj [ 5 ] . push_back ( 2 ) ; int dp1 [ n + 1 ] , dp2 [ n + 1 ] ; memset ( dp1 , 0 , sizeof dp1 ) ; memset ( dp2 , 0 , sizeof dp2 ) ;