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 <stdlib.h>


// 最大公約数を求める
long long int GCD (long long int a, long long int b) {
    long long int tmp, x, r;
    if (a<b) {
        tmp = a;
        a = b;
        b = tmp;
    }
    r = a % b;
    while (r!=0) {
      a = b;
      b = r;
      r = a % b;
    }
    return b;
}

int main() {
  long long int A, B, C, D, LCM;
  long long int result;
  scanf ("%lld %lld %lld %lld", &A, &B, &C, &D);
  
  
  LCM=C*D/GCD(C, D);
  
  result = B-A+1;
  
  result -= B / C;
  result -= B / D;
  result += B / LCM;
  result += (A-1) / C;
  result += (A-1) / D;
  result -= (A-1) / LCM;
  
  printf("%lld", result);
  return 0;
}