**Problem:**

In
ancient

Father
asks Pablo to take k pears (of course, he can only take the upper part of each
group first). Our lovely Pablo has just read the story about Kong Rong, so he decided to take out k pears whose total weight
is the lightest. Can you help him?

**Input:**

The
input consists of several test cases. Each test case consists of three lines:

The
first line consists of the number of the groups N (1=< N <= 5000) and K(1=<K<=10000), the times which Pablo should take.

The
second line contains N integers, and the ith integer refer to the weight of the lightest pear in the ith group.

The
third line also contains N integers, and the ith integer refer to the absolute weight difference between two
nearby pears in the ith group.

**Output:**

In
one line: the total weight of the k pears which Pablo should take.

**Sample input:**

2 3

5 1

10
5

4 4

3 5
6 6

2 8
2 2

**Sample output:**

12

19