import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.NoSuchElementException;

public class Main {

  private static long gcd(long a, long b) {
    return b == 0 ? a : gcd(b, a % b);
  }

  private void solve(FastScanner in, PrintWriter out) {
    while (true) {
      int m = in.nextInt();
      int n = in.nextInt();
      if (m == 0 && n == 0) {
        break;
      }
      int[] b = in.nextIntArray(m);
      int[] r = in.nextIntArray(n);

      Dinitz dinitz = new Dinitz(n + m + 2);
      int source = n + m;
      int sink = source + 1;
      for (int i = 0; i < m; i++) {
        for (int j = 0; j < n; j++) {
          if (gcd(b[i], r[j]) > 1) {
            dinitz.addEdge(i, j + m, 1);
          }
        }
      }

      for (int i = 0; i < m; i++) {
        dinitz.addEdge(source, i, 1);
      }
      for (int i = 0; i < n; i++) {
        dinitz.addEdge(i + m, sink, 1);
      }

      out.println(dinitz.maxFlow(source, sink));
    }
  }

  class Dinitz {

    class Edge {

      int to, rev;
      long cap;

      Edge(int to, long cap, int rev) {
        this.to = to;
        this.cap = cap;
        this.rev = rev;
      }
    }

    private ArrayDeque<Integer> deque = new ArrayDeque<>();
    private ArrayList<ArrayList<Edge>> g;
    private int[] level;
    private int[] iter;

    Dinitz(int V) {
      g = new ArrayList<>(V);
      for (int i = 0; i < V; i++) {
        g.add(new ArrayList<>());
      }
      level = new int[V];
      iter = new int[V];
    }

    void addEdge(int from, int to, long cap) {
      g.get(from).add(new Edge(to, cap, g.get(to).size()));
      g.get(to).add(new Edge(from, 0, g.get(from).size() - 1));
    }

    private long dfs(int v, int t, long f) {
      if (v == t) {
        return f;
      }
      for (; iter[v] < g.get(v).size(); iter[v]++) {
        Edge e = g.get(v).get(iter[v]);
        if (e.cap > 0 && level[v] < level[e.to]) {
          long d = dfs(e.to, t, Math.min(f, e.cap));
          if (d > 0) {
            e.cap -= d;
            g.get(e.to).get(e.rev).cap += d;
            return d;
          }
        }
      }
      return 0;
    }

    private void bfs(int s) {
      Arrays.fill(level, -1);
      level[s] = 0;
      deque.add(s);
      while (!deque.isEmpty()) {
        int v = deque.poll();
        for (Edge e : g.get(v)) {
          if (e.cap > 0 && level[e.to] < 0) {
            level[e.to] = level[v] + 1;
            deque.add(e.to);
          }
        }
      }
    }

    long maxFlow(int s, int t) {
      long flow = 0;
      for (; ; ) {
        bfs(s);
        if (level[t] < 0) {
          return flow;
        }
        Arrays.fill(iter, 0);
        long f;
        while ((f = dfs(s, t, Long.MAX_VALUE)) > 0) {
          flow += f;
        }
      }
    }
  }

  public static void main(String[] args) {
    PrintWriter out = new PrintWriter(System.out);
    new Main().solve(new FastScanner(), out);
    out.close();
  }

  private static class FastScanner {

    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) {
        return buffer[ptr++];
      } else {
        return -1;
      }
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) {
        ptr++;
      }
    }

    boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) {
        throw new NoSuchElementException();
      }
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    long nextLong() {
      if (!hasNext()) {
        throw new NoSuchElementException();
      }
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }

    public int[] nextIntArray(int n) {
      int[] array = new int[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextInt();
      }
      return array;
    }

    public long[] nextLongArray(int n) {
      long[] array = new long[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextLong();
      }
      return array;
    }

    public String[] nextStringArray(int n) {
      String[] array = new String[n];
      for (int i = 0; i < n; i++) {
        array[i] = next();
      }
      return array;
    }

    public char[][] nextCharMap(int n) {
      char[][] array = new char[n][];
      for (int i = 0; i < n; i++) {
        array[i] = next().toCharArray();
      }
      return array;
    }

    public int[][] nextIntMap(int n, int m) {
      int[][] map = new int[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextIntArray(m);
      }
      return map;
    }
  }
}

Measured memory_bytes: 121376