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 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <math.h>

int main(){
  long int A,B,C,D;
  scanf("%ld%ld%ld%ld",&A,&B,&C,&D);
  long int S,X;

  long int C1 = (B/C-(A-1)/C);
  long int D1 = (B/D-(A-1)/D);

  X = C * D;

  long int tmp;
  if(C<D){
    tmp = C;
    C = D;
    D = tmp;
  }

  long int R = C%D;
  while(R!=0){
    C = D;
    D = R;
    R = C%D;
  }
  R = X/D;

  S = (B-A+1) - C1 - D1 + (B/R-(A-1)/R);

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

  return 0;
}