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 gcdd(long long a,long long b){
  long long p=a;
  long long q=b;
  long long c=0;
  c = a%b;
  while(c != 0){
    p=q;
    q=c;
    c=p%q;
    //printf("%lld/",c);
  }
  return q;
}
  
int main(){
  long long a;
  long long b;
  long long c;
  long long d;
  long long upcnt=0;
  long long downcnt =0;
  long long cnt = 0;
  long long gcd = 0;
  scanf("%lld %lld %lld %lld",&a,&b,&c,&d);
  gcd = gcdd(c,d);
  //printf("%lld/",gcd);
  upcnt = b - b/c - b/d + b/(c*d/gcd);
  downcnt = a - a/c - a/d + a/(c*d/gcd);
  cnt = upcnt - downcnt;
  if(a % c != 0 && a % d != 0){
    cnt++;
    //printf("H");
  }
  printf("%lld",cnt);
  return 0;
}