2510. Bitwise Kingdom

In the Bitwise Kingdom, located somewhere in the universe, there are exactly 2^N citizens living and each of them has a unique identification string that represents his or her class in the society. An identification string is a binary string of length N which consists of characters ‘0’ or ‘1’. The order of classes is defined among the citizens by the following criteria:

1. Citizens identified by a string containing a greater number of ones are ranked higher. For example, “011” indicates a higher class than “100”.
2. Among those who have identification strings with the same number of ones, citizens identified by a lexicographically greater identification string are ranked higher. For example, “110” indicates a higher class than “101”.

For example, if N = 3, there are 8 (= 2³) people in the country, and their identification strings are “000”, “001”, “010”, “100”, “011”, “101”, “110”, and “111” (from the lowest class to the highest).

You are given two numbers N (1 ≤ N ≤ 60) and M (1 ≤ M ≤ 2^N), and you want to resolve the identification string of the person of the M-th lowest class among 2^N citizens. Can you write a program to solve this problem?