Books    boooks.X

A sequence of N (1 <= N <= 200) books on a bookshelf contains respectively
s_1, s_2, ..., s_N pages (1 <= s_i <= 10,000,000). These books must be
digitized by K employees (1 <= K <= 100). The first employee will process 0
or more of the books starting at s1; the second employee will process 0 or
more of the next books in sequence and so on. Each employee is paid d_1
dollars per page for her first processed book, d_2 dollars per page for her
second processed book, ..., d_i dollars per page (0 <= d_i <= 10,000,000)
for her i-th processed book.

Write a program to determine the minimum possible cost to process all the
books.

PROBLEM NAME: books

INPUT FORMAT:

* Line 1: Two space-separated integers, N and K

* Line 2: N space-separated integers, respectively s1, s2, ..., sN

* Line 3: N space-separated integers, respectively d1, d2, ..., dN

SAMPLE INPUT:

6 3
50 100 60 5 6 30
1 2 3 4 5 6

OUTPUT FORMAT:

* Line 1: A single line on the standard output, the minimal cost the
        employer has to pay to process all the books.

SAMPLE OUTPUT:

339