F. Fibonacci String Subsequences
time limit per test
3.5 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

You are given a binary string s (each character of this string is either 0 or 1).

Let's denote the cost of string t as the number of occurences of s in t. For example, if s is 11 and t is 111011, then the cost of t is 3.

Let's also denote the Fibonacci strings sequence as follows:

• F(0) is 0;
• F(1) is 1;
• F(i) = F(i - 1) + F(i - 2) if i > 1, where  +  means the concatenation of two strings.

Your task is to calculate the sum of costs of all subsequences of the string F(x). Since answer may be large, calculate it modulo 109 + 7.

Input

The first line contains two integers n and x (1 ≤ n ≤ 100, 0 ≤ x ≤ 100) — the length of s and the index of a Fibonacci string you are interested in, respectively.

The second line contains s — a string consisting of n characters. Each of these characters is either 0 or 1.

Output

Print the only integer — the sum of costs of all subsequences of the string F(x), taken modulo 109 + 7.

Examples
Input
2 411
Output
14
Input
10 1001010101010
Output
553403224