Consider an array where each integer from to (inclusive) can be made by either adding or subtracting numbers in the array. More rigorously, for every integer there exists two indices such that or . Furthermore, each array element must be an integer in the range , though they do not have to be distinct.
Your goal is to find and construct such an array with a length of at most .
The only line of input contains two integers and .
The first line should contain an integer , the length of the array you have found.
The next line should contain integers , the elements of the array.
2 3 16 4 8 5 13