Author:  ACM ICPC 20092010, NEERC, Northern Subregional Contest  Time limit:  3 sec  
Input file:  jealous.in  Memory limit:  256 Mb  
Output file:  jealous.out 
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 x^{k}. Let us say that a number n is pdominating over q if α(n, p)>α(n, q). Find out for how many numbers between a and b, inclusive are pdominating over q.
The first line of the input file contains a, b, p and q (1 ≤ a ≤ b ≤ 10^{18}; 2 ≤ p, q ≤ 10^{9}; p ≠ q; p and q are prime).
In the given example 3, 9, 15 and 18 are 3dominating over 2.
Output one number — how many numbers n between a and b, inclusive, are pdominating over q.
No.  Input file (jealous.in ) 
Output file (jealous.out ) 

1 

