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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
long HMY(long min,long max,long a){     //HowManyYakusuu
    return (long)(max/a) - (long)((min-1)/a);
}
long SKS(long a,long b){       //SaishouKoubaiSuu
    long x=a*b; 
    long c;
    if(a<b){
        c=a;
        a=b;
        b=c;
    }
    c=a%b;
    while(c!=0){
        a=b;
        b=c;
        c=a%b;
    }
    return x/b;
}
int main(){
    // Your code here!
    long A;
    long B;
    long C;
    long D;
    scanf("%ld %ld %ld %ld",&A,&B,&C,&D);
    printf("%ld",1+B-A-(HMY(A,B,C)+HMY(A,B,D)-HMY(A,B,SKS(C,D))));
  	return 0;
}