N = 2
     
       Q = [a1,b1] * [a2,b2]
       
      Sequential search
      For all  i , 1 <= i <= N, check if (Xi , Yi) belong to  Q
       
      Projection
      (1) For all i , check if Xi belong to [a1 , b1] ?
      (2) check if Yi belong to [a2,b2] ? among those i pass (1)
       
      Grid method (Atlas)
     
      Grid [0...4 , 0...4]
      Grid [0, 1] --> G, Z
 
      K-D tree (°Ñ¨£¤U¤@­¶)
     
     

      Quad-tree