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 Python (3.4.3) (judge verdict: Wrong Answer)

import fractions
A,B,C,D=map(int,input().split())
#B以下のものの数からA以下のものの数を引く
e=fractions.gcd(C,D)
a_c=(A-1)//C #A以下のCの倍数
b_c=B//C  #B以下のCの倍数
a_d=(A-1)//D
b_d=B//D
if e==C*D:
  s=A-1-(a_c+a_d)
  t=B-(b_c+b_d)
  u=t-s
  print(u)
else:
  a_cd=(A-1)//e #A以下のうちｃでもｄでも割り切れるもの
  b_cd=B//e
  s=A-1-(a_c+a_d-a_cd)
  t=B-(b_c+b_d-b_cd)
  u=t-s
  print(u)