B'Note that the memory limit in this problem is lower than in others. You have a vertical strip with n cells, numbered consecutively from 1 to n from top to bottom. You also have a token that is initially placed in cell n . You will move the token up until it arrives at cell 1 . Let the token be in cell x > 1 at some moment. One shift of the token can have either of the following kinds: Find the number of ways to move the token from cell n to cell 1 using one or more shifts, and print it modulo m . Note that if there are several ways to move the token from one cell to another in one shift, all these ways are considered distinct (check example explanation for a better understanding). The only line contains two integers n and m ( 2 <= n <= 4 cdot 10^6 ; 10^8 < m < 10^9 ; m is a prime number) -- the length of the strip and the modulo. Print the number of ways to move the token from cell n to cell 1 , modulo m . In the first test, there are three ways to move the token from cell 3 to cell 1 in one shift: using subtraction of y = 2 , or using division by z = 2 or z = 3 . There are also two ways to move the token from cell 3 to cell 1 via cell 2 : first subtract y = 1 , and then either subtract y = 1 again or divide by z = 2 . Therefore, there are five ways in total. '...