public class Solution {
    public static int commonPrimeDivisors(int[] a, int[] b) {
        int counter = 0;

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

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

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

        return counter;
    }

    private static int gcd(int n, int m) {
        if (n % m == 0) {
            return m;
        }

        return gcd(m, n % m);
    }

    private static int removeCommonPrimeDivisors(int n, int m) {
        while (n != 1) {
            int d = gcd(n, m);
            if (d == 1) {
                break;
            }
            n /= d;
        }

        return n;
    }
}