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 x,long long int y);
long long int GCD(long long int x,long long int y);
int main(){
    long long int a,b;
    long long int c,d;
    scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
   // long int count=0;
    //long int i;
    long long int A,B;
    A = (a-1) - ((a-1)/c + (a-1)/d - (a-1)/LCM(c,d));
    B = b - (b/c +b/d - b/LCM(c,d));
  //  printf("%lld\n",A);
   // printf("%lld\n",B);
    printf("%lld\n",B-A);
    return 0;
}
long long int GCD(long long int x,long long int y){
long long int r= x%y;
while(r!= 0){/*ユークリッドの互除法*/
x=y;
y=r;
r=x%y;
}
return y;
}

long long int LCM(long long int x,long long int y){
return ((x*y)/GCD(x,y)); //最小公倍数
}