G. String Rotation
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output

After studying strings in his college, Beshoy wants to create a problem on strings for you.

Given two strings $$$s$$$ and $$$t$$$ of length $$$n$$$ consisting of lowercase English letters, and an integer $$$x$$$.

You are allowed in one operation to change any character in the string $$$s$$$ to any character you want.

Your task is to count the minimum number of operations needed to make string $$$s$$$ equal to string $$$t$$$ after rotating $$$s$$$ exactly $$$x$$$ times to the right.

One cyclic shift to the right is such a transformation that the string $$$s=[s_{1},s_{2},...,s_{n}]$$$ becomes equal to the string $$$s=[s_{n},s_{1},s_{2},...,s_{n-1}]$$$.

Input

The first line contains two integers $$$n$$$ and $$$x$$$ $$$(1\leq n\leq 10^{5}, 1\leq x \leq 10^{9})$$$.

The second line contains string $$$s$$$ of length $$$n$$$.

The third line contains string $$$t$$$ of length $$$n$$$.

Output

Print one integer $$$-$$$ the minimum number of operations needed to make string $$$s$$$ equal to string $$$t$$$ after rotating $$$s$$$ exactly $$$x$$$ times to the right.

Example
Input
5 2
abcgh
ahcbg
Output
3