Given the values of k and n, find the number of positive integral solutions for the equation
Two positive integers k and n (k≤n≤100).
Print the number of positive integral solutions for the given equation. It is known that the answer is no more than 1018.
There are 3 positive integer solutions to the equation x1+x2+x3=4:
(1,1,2)
(1,2,1)
(2,1,1)