import java.io.*;
import java.util.stream.Stream;

public class BetweenTwoSets {
    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
             BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out))) {
            int[] firstLine = getArray(br.readLine());
            int[] firstArray = getArray(br.readLine());
            int[] secondArray = getArray(br.readLine());
            bw.write(String.valueOf(countNumbersBetweenSets(firstLine, firstArray, secondArray)));
            bw.flush();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private static int[] getArray(String line) throws IOException {
        return Stream.of(line.split(" ")).mapToInt(Integer::parseInt).toArray();
    }

    private static int countNumbersBetweenSets(int[] size, int[] firstArray, int[] secondArray) {
        int lcmOfFirst = calculateLcmOfArray(firstArray, size[0]);
        int gcdOfSecond = calculateGcdOfArray(secondArray, size[1]);

        int count = 0;
        int currentLcm = lcmOfFirst;
        while (currentLcm <= gcdOfSecond) {
            if (gcdOfSecond % currentLcm == 0) {
                count++;
            }
            currentLcm += lcmOfFirst;
        }
        return count;
    }

    private static int calculateLcmOfArray(int[] array, int size) {
        int result = array[0];
        for (int i = 1; i < size; i++) {
            result = lcm(result, array[i]);
        }
        return result;
    }

    private static int calculateGcdOfArray(int[] array, int size) {
        int result = array[0];
        for (int i = 1; i < size; i++) {
            result = gcd(result, array[i]);
        }
        return result;
    }

    private static int lcm(int a, int b) {
        if (a == 0 || b == 0)
            return 0;
        return Math.abs(a * b) / gcd(a, b);
    }

    private static int gcd(int a, int b) {
        if (b == 0)
            return a;
        return gcd(b, a % b);
    }
}