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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <cstdio>
#include <algorithm>
using namespace std;
long long A, B, C, D, ans, x; int t1, t2;
int main() {
  scanf("%ld %ld %ld %ld", &A, &B, &C, &D);
  t1 = min(C, D), t2 = max(C, D);
  for(int r = 1; r > 0;) {r = t2%t1; t2 = t1; t1 = r;}
  x = C*D/t2;
  ans = B-A+1;
  ans -= B/C-(A-1)/C+B/D-(A-1)/D;
  ans += B/x-(A-1)/x;
  printf("%ld", ans);
}