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)

function main(input) {
  const lines = input.split('\n');
  lines.forEach(line => {
    if (line.length === 0) {
      return;
    }
    const vs = line.split(' ');
    console.log(flow(
      parseInt(vs[0], 10),
      parseInt(vs[1], 10),
      parseInt(vs[2], 10),
      parseInt(vs[3], 10)
    ));
  });
}

function flow(a, b, c, d) {
  const m = gcd(c,d);
  return (b - a + 1) - count(a, b, c) - count(a, b, d) + count(a, b, (c*d) / m);
}

function count(min, max, devide) {
  const total = max / devide | 0;
  const diff = (min -1) / devide | 0;
  return total - diff;
}

function gcd(m, n) {
  var r;

  if(m < n) {  // m >= nにする
    r = m;  //一時退避
    m = n;
    n = r;
  }

  while ((r = m % n) != 0) {
    m = n;
    n = r;
  }

  return n;
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));