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<math.h>
long long UCLN(long long a, long long b)
   {
   	if (b==0) return a;
   	return UCLN(b,a%b);
   }
int main()
{
  long long i,a,b,demc=0,demd=0,demboi=0,boi=0;
  long long c,d,uoc;
  scanf("%lld%lld%lld%lld", &a, &b, &c, &d);
  if (c<d) uoc = UCLN(c,d);
   else uoc = UCLN(d,c);
  boi=(c*d)/(double)uoc;
  demc=b/c-a/c;
  if (a%c==0) demc++;
  demd=b/d-a/d;
  if (a%d==0) demd++;
  demboi=b/boi-a/boi;
  if (a%boi==0) demboi++;
 // printf("%lld %lld %lld ", demc, demd, demboi);
  printf("%lld", (b-a+1)-(demc+demd-demboi));
  return 0;
}