this problem consist subproblem solve subproblem d1 receive 3 point solve subproblem D2 receive 16 pointsManao chief architect involve plan new supercollider he identify plot land large possible supercollider build the supercollider building require fourway orthogonal collision particle travel speed consist accelerate chamber shape like plus sign ie each accelerate chamber length align Earths magnetic field parallel orthogonal minimize interferencethe accelerate chamber need lay long flat stretch land cost control Thus Manao commission topographical study identify possible maximal length tract land available building accelerate chamber parallel orthogonal Earths magnetic field to build large possible supercollider Manao identify large symmetric plus shape candidate tract that find tract land form axisaligne plus shape large distance center plus tip short arm plus Note collider need use entire length tract identify example note