//Author:xht37
#include <bits/stdc++.h>

#define ui unsigned int
#define ll long long
#define ul unsigned ll
#define ld long double

#define pi pair <int, int>
#define fi first
#define se second
#define mp make_pair

#define ls (p << 1)
#define rs (ls | 1)
#define md ((t[p].l + t[p].r) >> 1)

#define vi vector <int>
#define pb push_back
#define pq priority_queue

#define dbg(x) cerr << #x" = " << x << endl
#define debug(...) fprintf(stderr, __VA_ARGS__)

#define fl(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)

using namespace std;

namespace io {
	const int SI = 1 << 21 | 1;
	char IB[SI], *IS, *IT, OB[SI], *OS = OB, *OT = OS + SI - 1, c, ch[100];
	int f, t;
	#define gc() (IS == IT ? (IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT ? EOF : *IS++) : *IS++)
	inline void flush() {
		fwrite(OB, 1, OS - OB, stdout), OS = OB;
	}
	inline void pc(char x) {
		*OS++ = x;
		if (OS == OT) flush();
	}
	template <class I>
	inline void rd(I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + (c & 15), c = gc());
		x *= f;
	}
	template <class I>
	inline void rd(I &x, I &y) {
		rd(x), rd(y);
	}
	template <class I>
	inline void rd(I &x, I &y, I &z) {
		rd(x), rd(y), rd(z);
	}
	template <class I>
	inline void rda(I *a, int n) {
		for (int i = 1; i <= n; i++) rd(a[i]);
	}
	inline void rdc(char &c) {
		for (c = gc(); c < 33 || c > 126; c = gc());
	}
	inline void rds(char *s, int &x) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (x = 0; c >= 33 && c <= 126; s[++x] = c, c = gc());
		s[x+1] = '\0';
	}
	template <class I>
	inline void print(I x, char k = '\n') {
		if (!x) pc('0');
		if (x < 0) pc('-'), x = -x;
		while (x) ch[++t] = x % 10 + '0', x /= 10;
		while (t) pc(ch[t--]);
		pc(k);
	}
	template <class I>
	inline void print(I x, I y) {
		print(x, ' '), print(y);
	}
	template <class I>
	inline void print(I x, I y, I z) {
		print(x, ' '), print(y, ' '), print(z);
	}
	inline void printc(char c) {
		pc(c);
	}
	inline void prints(string s) {
		int x = s.length();
		while (t < x) pc(s[t++]);
		pc('\n'), t = 0;
	}
	struct Flush {
		~Flush() {
			flush();
		}
	} flusher;
}
using io::rd;
using io::rda;
using io::rdc;
using io::rds;
using io::print;
using io::printc;
using io::prints;

const int P = 1e9 + 7;

struct modint {
	int x;
	inline modint(int x = 0) : x(x) {}
	inline modint &operator = (int o) { return x = o, *this; }
	inline modint &operator += (modint o) { return x = x + o.x >= P ? x + o.x - P : x + o.x, *this; }
	inline modint &operator -= (modint o) { return x = x - o.x < 0 ? x - o.x + P : x - o.x, *this; }
	inline modint &operator *= (modint o) { return x = 1ll * x * o.x % P, *this; }
	inline modint &operator ^= (ll b) {
		modint a = *this, c;
		if (!~b) b = P - 2;
		c.x = 1 % P;
		while (b) {
			if (b & 1) c *= a;
			a *= a, b >>= 1;
		}
		return x = c.x, *this;
	}
	inline modint &operator /= (modint o) { return *this *= o ^= -1; }
	inline modint &operator += (int o) { return x = x + o >= P ? x + o - P : x + o, *this; }
	inline modint &operator -= (int o) { return x = x - o < 0 ? x - o + P : x - o, *this; }
	inline modint &operator *= (int o) { return x = 1ll * x * o % P, *this; }
	inline modint &operator /= (int o) { modint y = modint(o); return *this *= y ^= -1; }
	template <class I>
	inline friend modint operator + (modint a, I b) { return a += b; }
	template <class I>
	inline friend modint operator - (modint a, I b) { return a -= b; }
	template <class I>
	inline friend modint operator * (modint a, I b) { return a *= b; }
	inline friend modint operator ^ (modint a, ll b) { return a ^= b; }
	template <class I>
	inline friend modint operator / (modint a, I b) { return a /= b; }
	inline friend bool operator == (modint a, int b) { return a.x == b; }
	inline friend bool operator != (modint a, int b) { return a.x != b; }
	inline friend bool operator < (modint a, int b) { return a.x < b; }
	inline friend bool operator <= (modint a, int b) { return a.x <= b; }
	inline friend bool operator > (modint a, int b) { return a.x > b; }
	inline friend bool operator >= (modint a, int b) { return a.x >= b; }
	inline friend bool operator == (modint a, modint b) { return a.x == b.x; }
	inline friend bool operator != (modint a, modint b) { return a.x != b.x; }
	inline friend bool operator < (modint a, modint b) { return a.x < b.x; }
	inline friend bool operator <= (modint a, modint b) { return a.x <= b.x; }
	inline friend bool operator > (modint a, modint b) { return a.x > b.x; }
	inline friend bool operator >= (modint a, modint b) { return a.x >= b.x; }
	inline bool operator ! () { return !x; }
	inline modint operator - () { return x ? P - x : 0; }
};
inline void rd(modint &x) { rd(x.x); }
inline void print(modint x, char k = '\n') { print(x.x, k); }

//const int NP = NP;
//modint p[NP], v[NP], vp[NP];
//inline void init(int n) {
//  p[0] = v[0] = 1;
//  for (int i = 1; i <= n; i++) p[i] = p[i-1] * i;
//  vp[n] = 1 / p[n];
//  for (int i = n; i; i--) v[i] = vp[i] * p[i-1], vp[i-1] = vp[i] * i;
//}
//inline modint binom(int n, int m) {
//  return n < m ? 0 : p[n] * vp[m] * vp[n-m];
//}

const int N = 1e5 + 7;
int n, m, a[N], b[N], x[N], y[N], X[N], Y[N], p[N], t;
struct BIT {
	vector<modint> c;
	inline BIT() {}
	inline BIT(int n) { c.resize(n); }
	inline void add(ui x, modint k) {
		while (x < c.size()) c[x] += k, x += x & -x;
	}
	inline modint ask(ui x) {
		modint k = 0;
		while (x) k += c[x], x -= x & -x;
		return k;
	}
};

int main() {
	rd(n), rd(m), rda(a, n), rda(b, m);
	for (int i = 1; i <= n; i++) {
		if (a[i] < b[1] || a[i] > b[m]) continue;
		int p = upper_bound(b + 1, b + m + 1, a[i]) - b;
		x[++t] = a[i] - b[p-1], y[t] = b[p] - a[i], ::p[t] = t;
		X[t] = x[t], Y[t] = y[t];
	}
	sort(X + 1, X + t + 1), sort(Y + 1, Y + t + 1);
	int u = unique(X + 1, X + t + 1) - X - 1;
	int v = unique(Y + 1, Y + t + 1) - Y - 1;
	for (int i = 1; i <= t; i++)
		x[i] = lower_bound(X + 1, X + u + 1, x[i]) - X,
		y[i] = lower_bound(Y + 1, Y + v + 1, y[i]) - Y;
	sort(p + 1, p + t + 1, [&](int i, int j) {
		return x[i] == x[j] ? y[i] > y[j] : x[i] < x[j];
	});
	t = unique(p + 1, p + t + 1, [&](int i, int j) {
		return x[i] == x[j] && y[i] == y[j];
	}) - p - 1;
	BIT c(v + 1);
	modint ans = 1, now;
	for (int i = 1; i <= t; i++)
		ans += now = c.ask(y[p[i]] - 1) + 1, c.add(y[p[i]], now);
	print(ans);
	return 0;
}

Measured memory_bytes: 7040