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 (GCC 9.2.1) (judge verdict: Accepted)

#include <stdio.h>

long gojo(long a, long b){
  if(a % b)
    gojo(b, a%b);
  else
    return b;
}

int main(){
  long a, b, c, d;  scanf("%ld%ld%ld%ld", &a, &b, &c, &d);

  long ans = b - a + 1;
  ans = ans - ((b/c) - (a-1)/c);
  ans = ans - ((b/d) - (a-1)/d);

  long g = c/gojo(c, d)*d;
  ans = ans + ((b/g) - (a-1)/g);

  printf("%ld\n", ans);

  return 0;
}