A group of school leavers had their graduation party at an aquapark. They had a great time, but when they were leaving the aquapark they were surprised by a suddenly cold weather and a heavy rain, which made it quite a problem to get to the trolleybus stop.
It turned out that all the boys in the company had their umbrellas and all the girls were without umbrellas. Of course, each boy, being a real gentleman, volunteered to accompany one of the girls to the trolleybus stop under his umbrella.
If theith girl gets wet under the rain, she’ll get upset bygiunits. If no girl accepts an invitation from thejth boy, he’ll get upset bybj·kunits, wherekis the number of luckier boys who will accompany girls under their umbrellas. The girls who will go under umbrellas and the accompanying boys will not get upset at all.
Help the boys and girls keep their holiday mood as unspoiled as possible. Determine how they should proceed to make the total upset minimal.
，偶尔会想，如果人生真如一场电子游戏，
