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 lcm(long long int c, long long int d);
long long int gcd(long long int c, long long int d);
int main()
{
    long long int a,b,c,d,res;
    
    scanf("%lld%lld%lld%lld",&a,&b,&c,&d);
    
long long int     p=b/c;
long long int     q=(a-1)/c;
long long int     r=b/d;
long long int     s=(a-1)/d;
long long int     t=b/lcm(c,d);
long long int     u=(a-1)/lcm(c,d);
    
    res=(b-(a-1))-(p-q+r-s-(t-u));
    
    printf("%lld",res);
    
}
long long int gcd(long long int c, long long int d)
{
    if(c==0)
    return d;
    else 
    return gcd(d%c,c);
}
long long int lcm(long long int c,long long int d)
{   
   long long  int p=(c*d)/gcd(c,d);
    return p;
}