【URAL 1056】Amount of Degree

Amount of Degrees
Time Limit: 1000MS Memory Limit: 65536KB 64bit IO Format: %I64d & %I64u

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Description
Create a code to determine the amount of integers, lying in the set [ X; Y] and being a sum of exactly K different integer degrees of B.
Example. Let X=15, Y=20, K=2, B=2. By this example 3 numbers are the sum of exactly two integer degrees of number 2:
17 = 2 4+2 0,
18 = 2 4+2 1,
20 = 2 4+2 2.

Input
The first line of input contains integers X and Y, separated with a space (1 ≤ X ≤ Y ≤ 2 31−1). The next two lines contain integers K and B (1 ≤ K ≤ 20; 2 ≤ B ≤ 10).

Output
Output should contain a single integer — the amount of inte