Chef and Stones

Chef is playing a game. Currently in the game, he is at a field full of stones. There are total N kinds of stones. There is unlimited supply of each kind of stone. Chef knows that one stone of kind i needs Ai minutes to pick it from the ground and it will give Chef a profit of Bi Rs. Chef has K minutes of free time. During this free time, Chef want to pick stones so as to maximize his profit. Bu