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: Wrong Answer)

#include <stdio.h>
 
long long int gcd(long long int a, long long int b);
 
int main(){
    long long int a, b, c, d;
    long long int cntb=0,cnta=0;
 
    scanf("%lld %lld %lld %lld", &a, &b, &c, &d);
 
    cntb = b;
 
    cntb -= b / c;
    cntb -= b / d;
 
    cntb += b / ((c * d) / gcd(c, d));
  
  	cnta = a-1;
  	cnta -= (a-1)/c;
  	cnta -= (a-1)/d;
  
 	cnta += (a-1)/((c*b)/gcd(c,d));
 
    printf("%lld\n", cntb-cnta);
 
    return 0;
 
}
 
long long int gcd(long long int a, long long int b){
  long long int work;
  	if(a<b){
  	  work = a;
  	  a = b;
  	  b = work;
	}
    long long int r = a % b;
    while(r!=0){
        a = b;
        b = r;
        r = a % b;
    }
 
    return b;
}