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>
int main(){
  unsigned long long int in1,in2,in3,in4,r,a,b,lcm,sum = 0;
  scanf("%lld %lld %lld %lld",&in1 ,&in2 ,&in3 ,&in4);
  //sum = in2 - in1 + 1;
  
  if(in3 < in4){
    a = in4; b = in3;
  }else{
    b = in4; a = in3;
  }
  
  sum += (in2 - in1 + 1) - ((in2/in3) - (in1 - 1)/in3 + (in2/in4) - (in1 - 1)/in4);
  
  r = a % b;
  while(r != 0){
    a = b;
    b = r;
    r = a % b;
  }
  
  lcm = in3 * in4 / b;
  sum += (in2/lcm) - (in1 - 1)/lcm;
  
  printf("%llu\n",sum);

  return 0;
}