#include <bits/stdc++.h>
#define ADD(a, b) a = (a + ll(b)) % mod
#define MUL(a, b) a = (a * ll(b)) % mod
#define MAX(a, b) a = max(a, b)
#define MIN(a, b) a = min(a, b)
#define rep(i, a, b) for(int i = int(a); i < int(b); i++)
#define rer(i, a, b) for(int i = int(a) - 1; i >= int(b); i--)
#define all(a) (a).begin(), (a).end()
#define sz(v) (int)(v).size()
#define pb push_back
#define sec second
#define fst first
#define debug(fmt, ...) Debug(__LINE__, ":", fmt, ##__VA_ARGS__)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<int, pi> ppi;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<vl> mat;
typedef complex<double> comp;
void Debug() {cout << '\n'; }
template<class FIRST, class... REST>void Debug(FIRST arg, REST... rest){
	cout<<arg<<" ";Debug(rest...);}
template<class T>ostream& operator<<(ostream& out,const vector<T>& v) {
	out<<"[";if(!v.empty()){rep(i,0,sz(v)-1)out<<v[i]<<", ";out<<v.back();}out<<"]";return out;}
template<class S, class T>ostream& operator<<(ostream& out,const pair<S, T>& v){
	out<<"("<<v.first<<", "<<v.second<<")";return out;}
const int MAX_N = 200010;
const int MAX_V = 100010;
const double eps = 1e-6;
const ll mod = 1000000007;
const int inf = 1 << 30;
const ll linf = 1LL << 60;
const double PI = 3.14159265358979323846;
///////////////////////////////////////////////////////////////////////////////////////////////////

struct BIT { //0-origin!!! update and get just like lazy_segtree
	int n; vl bit0, bit1;
	void init(int mx) {
		n = mx;
		bit0 = vl(n + 1, 0); bit1 = vl(n + 1, 0);
	}
	BIT(int mx = 0) { init(mx); } 

	ll ga(vl& bit, int i) {
		ll s = 0;
		while(i > 0) { ADD(s, bit[i]); i -= i & -i; }
		return s;
	}
	void app(vl& bit, int i, ll x) {
		while(i <= n) { ADD(bit[i], x); i += i & -i; }
	}
	void update(int a, int b, ll x) { //[a, b)
		a++;
		app(bit0, a, -x * (a - 1));
		app(bit1, a, x);
		app(bit0, b + 1, x * b);
		app(bit1, b + 1, -x);
	}
	ll get(int a, int b) { //[a, b)
		a++;
		return ((ga(bit1, b) * b % mod + ga(bit0, b) % mod) % mod 
			- (ga(bit1, a - 1) * (a - 1) % mod + ga(bit0, a - 1) % mod) + mod) % mod;
	}
};

int N, M;
ll X[MAX_N], Y[MAX_N];
ll L[MAX_N], R[MAX_N];
vl vec;
vl Q[MAX_N];

int fd(ll v) {
	return lower_bound(all(vec), v) - vec.begin();
}

void solve() {
	cin >> N >> M;
	rep(i, 0, N) cin >> X[i + 1];
	rep(i, 0, M) cin >> Y[i + 1];
	X[0] = -linf;
	Y[M + 1] = linf;
	int at = 1;
	rep(i, 0, N) {
		while(X[i + 1] > Y[at]) at++;
		if(at != M + 1) R[i] = Y[at] - X[i + 1];
		else R[i] = linf;
		vec.pb(R[i]);
	}
	at = M;
	rer(i, N, 0) {
		while(X[i + 1] < Y[at]) at--;
		if(at != 0) L[i] = X[i + 1] - Y[at];
		else L[i] = linf;
		vec.pb(L[i]);
	}
	vec.pb(linf);
	sort(all(vec));
	// debug(vl(L, L + N));
	// debug(vl(R, R + N));
	vec.erase(unique(all(vec)), vec.end());
	rep(i, 0, N) {
		int lat = fd(L[i]), rat = fd(R[i]);
		Q[lat].pb(rat);
	}
	rep(i, 0, sz(vec)) {
		sort(all(Q[i]));
		Q[i].erase(unique(all(Q[i])), Q[i].end());
	}
	BIT bit(sz(vec));
	bit.update(sz(vec) - 1, sz(vec), 1);
	rer(i, sz(vec) - 1, 0) {
		rep(j, 0, sz(Q[i])) {
			int b = Q[i][j];
			ll v = bit.get(b + 1, sz(vec));
			// debug(vec[i], vec[b], v);
			bit.update(b, b + 1, v);
		}
	}
	cout << bit.get(0, sz(vec)) << "\n";
}

int main() {
#ifndef LOCAL
	ios::sync_with_stdio(false);
    cin.tie(0);
#endif
    cout << fixed;
	cout.precision(20);
	srand((unsigned int)time(NULL));
#ifdef LOCAL
	//freopen("in.txt", "wt", stdout); //for tester
    freopen("in.txt", "rt", stdin);
#endif	
	solve();
#ifdef LOCAL
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << " s.\n";
#endif
	return 0;
}



Measured memory_bytes: 18288