N位同学站成一排，音乐老师要请其中的(N-K)位同学出列，使得剩下的K位同学排成合唱队形。任务是，已知所有N位同学的身高，计算最少需要几位同学出列，可以使得剩下的同学排成合唱队形-N students stand in a row, music teachers have to ask them (NK) students out of which the remaining students K chorus line formation. Task is known to students