You are given an integer m . Let M = 2 m - 1 . You are also given a set of n integers denoted as the set T . The integers will be provided in base 2 as n binary strings of length m . A set of integers S is called "good" if the following hold. If , then . If , then All elements of S are less than or equal to M . Here, and refer to the bitwise XOR and bitwise AND operators, respectively. Count the number of good sets S , modulo 10 9 + 7 . The first line will contain two integers m and n ( 1 ≤ m ≤ 1 000 , 1 ≤ n ≤ min (2 m , 50) ). The next n lines will contain the elements of T . Each line will contain exactly m zeros and ones. Elements of T will be distinct. Print a single integer, the number of good sets modulo 10 9 + 7 . An example of a valid set S is {00000, 00101, 00010, 00111, 11000, 11010, 11101, 11111}.