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 (3.8.2) (judge verdict: Accepted)

a,b,c,d = map(int,input().split())

def mul_count(v,w,n):
  if v % n == 0:
    s = v//n
  else:
    s = v//n + 1
  e = w // n
  if s > e:
    return 0
  else:
    return e - s + 1

def koyaku(x,y):
  big = max(x,y)
  small= min(x,y)
  amari = big % small
  if amari == 0:
    return small
  else:
    return koyaku(small,amari)

c_mul = mul_count(a,b,c)
d_mul = mul_count(a,b,d)

cd_common = koyaku(c,d)
cd_mul = c * d // cd_common
common_mul = mul_count(a,b,cd_mul)
yobun = c_mul + d_mul - common_mul
print(b - a + 1 - yobun)