|Author:||ACM ICPC 2009-2010, NEERC, Northern Subregional Contest||Time limit:||3 sec|
|Input file:||jealous.in||Memory limit:||256 Mb|
There is a trouble in Numberland, prime number p is jealous of another prime number q. She thinks that there are more integer numbers between a and b, inclusively, that are divisible by greater power of q than that of p. Help p to get rid of her feelings.
Let α(n, x) be maximal k such that n is divisible by xk. Let us say that a number n is p-dominating over q if α(n, p)>α(n, q). Find out for how many numbers between a and b, inclusive are p-dominating over q.
The first line of the input file contains a, b, p and q (1 ≤ a ≤ b ≤ 1018; 2 ≤ p, q ≤ 109; p ≠ q; p and q are prime).
In the given example 3, 9, 15 and 18 are 3-dominating over 2.
Output one number — how many numbers n between a and b, inclusive, are p-dominating over q.
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