import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Comparator;
import java.util.InputMismatchException;

//
// 	// -1 1
// -2 1
// -1 2
// -2 2
// B->D->C
//  ->A/


public class Main {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	static void solve()
	{
		int n = ni(), m = ni();
		int[] a = na(n);
		int[] b = na(m);
		
		int[][] rs = new int[n][];
		int p = 0;
		for(int i = 0;i < n;i++){
			int l = Arrays.binarySearch(b, a[i]);
			if(l < 0)l = -l-2;
			int r = l+1;
			if(l < 0 || r >= m)continue;
			rs[p++] = new int[]{b[l] - a[i], b[r] - a[i]};
		}
		if(p == 0){
			out.println(1);
			return;
		}
		
		rs = Arrays.copyOf(rs, p);
		n = p;
		
		Arrays.sort(rs, new Comparator<int[]>() {
			public int compare(int[] a, int[] b) {
				if(a[0] != b[0])return a[0] - b[0];
				return a[1] - b[1];
			}
		});
		
		p = 0;
		for(int i = 0;i < n;i++){
			if(i > 0 && Arrays.equals(rs[i], rs[i-1])){
			}else{
				rs[p++] = rs[i];
			}
		}
		rs = Arrays.copyOf(rs, p);
		n = p;
		
		int[] ys = new int[n];
		for(int i = 0;i < n;i++){
			ys[i] = rs[i][1];
		}
		ys = shrink(ys);
		for(int i = 0;i < n;i++){
			rs[i][1] = ys[i];
		}
		
		long[] ft = new long[n+10];
		addFenwick(ft, 0, 1);
		for(int i = n-1;i >= 0;i--){
			addFenwick(ft, rs[i][1]+1, sumFenwick(ft, rs[i][1]));
//			tr(restoreFenwick(ft));
		}
		out.println(sumFenwick(ft, n));
	}
	
	public static long[] restoreFenwick(long[] ft)
	{
		int n = ft.length-1;
		long[] ret = new long[n];
		for(int i = 0;i < n;i++)ret[i] = sumFenwick(ft, i);
		for(int i = n-1;i >= 1;i--){
			ret[i] -= ret[i-1];
			if(ret[i] < 0)ret[i] += mod;
		}
		return ret;
	}

	
	public static int[] shrink(int[] a) {
		int n = a.length;
		long[] b = new long[n];
		for (int i = 0; i < n; i++)
			b[i] = (long) a[i] << 32 | i;
		Arrays.sort(b);
		int[] ret = new int[n];
		int p = 0;
		for (int i = 0; i < n; i++) {
			if (i > 0 && (b[i] ^ b[i - 1]) >> 32 != 0)
				p++;
			ret[(int) b[i]] = p;
		}
		return ret;
	}

	
	public static final int mod = 1000000007;
	
	public static long sumFenwick(long[] ft, int i)
	{
		long sum = 0;
		for(i++;i > 0;i -= i&-i){
			sum += ft[i];
			if(sum >= mod)sum -= mod;
		}
		return sum;
	}
	
	public static void addFenwick(long[] ft, int i, long v)
	{
		v %= mod;
		if(v < 0)v += mod;
		if(v == 0)return;
		int n = ft.length;
		for(i++;i < n;i += i&-i){
			ft[i] += v;
			if(ft[i] >= mod)ft[i] -= mod;
		}
	}

	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
//	private static boolean isSpaceChar(int c) { return !(c >= 32 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private static char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}


Measured memory_bytes: 32860