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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

const input = require("fs").readFileSync("/dev/stdin", "utf8");

const data = input.split('\n')[0].split(' ');
const A = +data[0];
const B = +data[1];
const C = +data[2];
const D = +data[3];

const y = (n, m) => m ? y(m, n % m) : n;
const sky = (n, m) => {
  return n * m / y(n, m);
};

const CD = sky(C, D);

const banA = Math.floor((A - 1) / C) + Math.floor((A - 1) / D) - Math.floor((A - 1) / CD);
const a = (A - 1) - banA;

const banB = Math.floor(B / C) + Math.floor(B / D) - Math.floor(B / CD);
const b = (B - banB);

console.log(b - a);