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>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <stdbool.h>
#define LL long long
#define INF 1<<31-1
#define MIN(x,y) ((x)<(y)?(x):(y))
#define MAX(x,y) ((x)<(y)?(y):(x))
#define FOR(i,a,n) for(i=a;i<n;i++)
#define MOD 1000000007
#define NUM 100005
void swap(int* a,int* b){int tmp=*a;*a=*b;*b=tmp;}
int cmp(const void* a,const void* b){return *(int*)a-*(int*)b;}

LL GCD(LL x,LL y){
  int z=1,tmp=MAX(x,y);
  y=MIN(x,y);
  x=tmp;
  while(z!=0){
    z=x%y;
    x=y;
    y=z;
  }
  return x;
}

int main() {
  LL A,B,C,D,i,ans=0;
  scanf("%lld%lld%lld%lld",&A,&B,&C,&D);
  LL E=C*D/GCD(C,D);
  A--;
  ans=B-B/C-B/D+B/E-(A-A/C-A/D+A/E);

  printf("%lld\n",ans);
	return 0;
}