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>

long long int gcd (long long int ,long long int );

int main(){
  long long int A,B,C,D;
  long long int lcmCD;
  
  scanf("%lld %lld %lld %lld",&A,&B,&C,&D);

  if( C > D )
    lcmCD = C/gcd(C,D)*D;
  else
    lcmCD = C/gcd(D,C)*D;  

  printf("%lld\n", (B-(A-1)) - (B/C-(A-1)/C) - (B/D-(A-1)/D) + (B/lcmCD-(A-1)/lcmCD) );
  
  return 0;
}

long long int gcd(long long int x,long long int y){
  if(y==0)
    return x;
  else 
    return gcd(y,x%y);
}