#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define all(c) c.begin(),c.end()
#define pb push_back
#define fs first
#define sc second
#define chmin(x,y) x=min(x,y)
#define chmax(x,y) x=max(x,y)
using namespace std;
template<class S,class T> ostream& operator<<(ostream& o,const pair<S,T> &p){
	return o<<"("<<p.fs<<","<<p.sc<<")";
}
template<class T> ostream& operator<<(ostream& o,const vector<T> &vc){
	o<<"{";
	for(const T& v:vc) o<<v<<",";
	o<<"}";
	return o;
}
using ll = long long;
template<class T> using V = vector<T>;
template<class T> using VV = vector<vector<T>>;
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n-1); }

#ifdef LOCAL
#define show(x) cerr << "LINE" << __LINE__ << " : " << #x << " = " << (x) << endl
#else
#define show(x) true
#endif
template<unsigned int mod_>
struct ModInt{
	using uint = unsigned int;
	using ll = long long;
	using ull = unsigned long long;

	constexpr static uint mod = mod_;

	uint v;
	ModInt():v(0){}
	ModInt(ll _v):v(normS(_v%mod+mod)){}
	explicit operator bool() const {return v!=0;}
	static uint normS(const uint &x){return (x<mod)?x:x-mod;}		// [0 , 2*mod-1] -> [0 , mod-1]
	static ModInt make(const uint &x){ModInt m; m.v=x; return m;}
	ModInt operator+(const ModInt& b) const { return make(normS(v+b.v));}
	ModInt operator-(const ModInt& b) const { return make(normS(v+mod-b.v));}
	ModInt operator-() const { return make(normS(mod-v)); }
	ModInt operator*(const ModInt& b) const { return make((ull)v*b.v%mod);}
	ModInt operator/(const ModInt& b) const { return *this*b.inv();}
	ModInt& operator+=(const ModInt& b){ return *this=*this+b;}
	ModInt& operator-=(const ModInt& b){ return *this=*this-b;}
	ModInt& operator*=(const ModInt& b){ return *this=*this*b;}
	ModInt& operator/=(const ModInt& b){ return *this=*this/b;}
	ModInt& operator++(int){ return *this=*this+1;}
	ModInt& operator--(int){ return *this=*this-1;}
	ll extgcd(ll a,ll b,ll &x,ll &y) const{
		ll p[]={a,1,0},q[]={b,0,1};
		while(*q){
			ll t=*p/ *q;
			rep(i,3) swap(p[i]-=t*q[i],q[i]);
		}
		if(p[0]<0) rep(i,3) p[i]=-p[i];
		x=p[1],y=p[2];
		return p[0];
	}
	ModInt inv() const {
		ll x,y;
		extgcd(v,mod,x,y);
		return make(normS(x+mod));
	}
	ModInt pow(ll p) const {
		if(p<0) return inv().pow(-p);
		ModInt a = 1;
		ModInt x = *this;
		while(p){
			if(p&1) a *= x;
			x *= x;
			p >>= 1;
		}
		return a;
	}
	bool operator==(const ModInt& b) const { return v==b.v;}
	bool operator!=(const ModInt& b) const { return v!=b.v;}
	friend istream& operator>>(istream &o,ModInt& x){
		ll tmp;
		o>>tmp;
		x=ModInt(tmp);
		return o;
	}
	friend ostream& operator<<(ostream &o,const ModInt& x){ return o<<x.v;}
};
using mint = ModInt<1000000007>;

struct BIT{
	using D = mint;
	int N;
	vector<D> bit;
	BIT(int n){		//nは区間幅!!!
		N=n;
		bit.assign(n+1,0);
	}
	BIT(){}
	D sum(int i){		//i個の和a[0]+..a[i-1]
		D s=0;
		while(i>0){
			s+=bit[i];
			i-=(i&-i);
		}
		return s;
	}
	D val(int i){	//return a[i]	(0-ind)
		return sum(i+1)-sum(i);
	}
	void add(int i,D x){	//a[i]+=x (0-indexed)
		i++;
		while(i<=N){
			bit[i]+=x;
			i+=(i&-i);
		}
	}
};

using P = pair<ll,ll>;

mint solve(V<P> ps){
	sort(all(ps),[&](P& l, P& r){
		return P(l.fs,-l.sc) < P(r.fs,-r.sc);
	});
	int N = ps.size();
	BIT bit(N);
	mint ans = 1;
	for(P p: ps){
		mint v = bit.sum(p.sc) + 1;
		bit.add(p.sc,v);
		ans += v;
	}
	return ans;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);		//DON'T USE scanf/printf/puts !!
	cout << fixed << setprecision(20);
	
	int N,M;
	cin >> N >> M;
	V<ll> x(N),y(M);
	rep(i,N) cin >> x[i];
	rep(i,M) cin >> y[i];
	using P = pair<ll,ll>;
	V<P> ps;
	rep(i,N){
		if(x[i] < y.front() || x[i] > y.back()) continue;
		int lid = lower_bound(all(y),x[i]) - y.begin() - 1;
		ps.emplace_back(x[i]-y[lid],y[lid+1]-x[i]);
	}
	sort(all(ps));
	ps.erase(unique(all(ps)),ps.end());
	V<ll> ys;
	for(P p: ps) ys.pb(p.sc);
	sort(all(ys));
	ys.erase(unique(all(ys)),ys.end());
	for(P& p: ps) p.sc = lower_bound(all(ys),p.sc) - ys.begin();
	cout << solve(ps) << endl;
}


Measured memory_bytes: 6768