function commonPrimeDivisors(a: number[], b: number[]): number {
  const gcd = (n: number, m: number): number => (n % m === 0 ? m : gcd(m, n % m));

  const removeCommonPrimeDivisors = (n: number, m: number): number => {
    while (n !== 1) {
      const d = gcd(n, m);
      if (d === 1) {
        break;
      }
      n /= d;
    }

    return n;
  };

  let counter = 0;
  for (let i = 0; i < a.length; i++) {
    let x = a[i];
    let y = b[i];
    const d = gcd(x, y);

    x = removeCommonPrimeDivisors(x, d);
    if (x !== 1) {
      continue;
    }

    y = removeCommonPrimeDivisors(y, d);
    if (y === 1) {
      counter++;
    }
  }

  return counter;
}