Problem:
Score : 300 points

Problem Statement

You are given four integers A, B, C, and D. Find the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Constraints

1\leq A\leq B\leq 10^{18}

1\leq C,D\leq 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C D

Output

Print the number of integers between A and B (inclusive) that can be evenly divided by neither C nor D.

Sample Input 1

4 9 2 3

Sample Output 1

2

5 and 7 satisfy the condition.

Sample Input 2

10 40 6 8

Sample Output 2

23

Sample Input 3

314159265358979323 846264338327950288 419716939 937510582

Sample Output 3

532105071133627368

Solution in Fortran (gfortran v4.8.4) (judge verdict: Wrong Answer)

program ccc
implicit none
integer(16) res
integer(16) a, b, c, d, x, y, z
integer(16) s
read*, a, b, c, d
x=max(c,d)
y=min(c,d)
res=1
z=c*d
 do while (res.ne.0)
 res=mod(x,y)
 if(res.ne.0) then
 y=res
 end if
 if(res.eq.0) then
 z=(c*d)/y
 end if
 end do
s=int(b/c)+int(b/d)-int((a-1)/c)-int((a-1)/d)-int(b/(z))+int((a-1)/(z))
s=(b-a+1)-s
print*, s, z
end program