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>

int main(){

    unsigned long a,b,c,d;
    scanf("%ld %ld %ld %ld",&a,&b,&c,&d);
    
    unsigned long count=0;
    count += b-a+1;
    int x=c*d;
    count -= (b/c)-((a-1)/c)+(b/d)-((a-1)/d);

    int r = d % c;
    while(r!=0){
        d=c;
        c=r;
        r=d%c;
    }

    count += (b/(x/c))-((a-1)/(x/c));
        
    printf("%ld\n",count);

    return 0;
}