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: Runtime Error)

#include<stdio.h>
int main(void){
    unsigned long long int A,B,C,D;
    unsigned long long int g,k,j,r,a,b;
    scanf("%lld %lld %lld %lld",&A,&B,&C,&D);
    g=B/C-(A-1)/C;
    a=A;
    b=B;
    r = a % b;
    while(r!=0){
        a = b;
        b = r;
        r = a % b;
    }
    r=(D*C)/b;

    k=B/D-(A-1)/D;

    j=B/r-(A-1)/r;
    printf("%lld\n",B-A+1-g-k+j);
    return 0;
}