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>

int GDC(int a, int b){
    if(a==0){
        return b;
    }else if(b==0){
        return a;
    }
    if(a<b){
        GDC(a,b%a);
    }else{
        GDC(a%b, b);
    }
}

int main(){
    long long int A, B, C, D;
    long long int sub, sumC, sumD, sumCD;
    long long int gdcCD;

    scanf("%ld %ld %ld %ld", &A, &B, &C, &D);

    gdcCD =  GDC(C,D);

    sub = B-A+1;
    sumC = B/C-(A-1)/C;
    sumD = B/D-(A-1)/D;
    sumCD = B/(C*D/gdcCD)-(A-1)/(C*D/gdcCD);;

    printf("%ld", sub-sumC-sumD+sumCD);

    return 0;
}