there n distinct point coordinate line coordinate ith point equal x_i choose subset give set point distance pair point subset integral power it necessary consider pair point adjacent Note subset contain element satisfie condition among subset choose subset maximum possible sizein word choose maximum possible number point x_i_1 x_i_2 dot x_i_m pair x_i_j x_i_k true x_i_j x_i_k 2d d nonnegative integer number necessarily pair point