#include <bits/stdc++.h>
#include <sys/types.h>
#include <unistd.h>

#define _overload(_1,_2,_3,name,...) name
#define _rep(i,n) _range(i,0,n)
#define _range(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload(__VA_ARGS__,_range,_rep,)(__VA_ARGS__)

#define _rrep(i,n) _rrange(i,n,0)
#define _rrange(i,a,b) for(int i=int(a)-1;i>=int(b);--i)
#define rrep(...) _overload(__VA_ARGS__,_rrange,_rrep,)(__VA_ARGS__)

#define _all(arg) begin(arg),end(arg)
#define uniq(arg) sort(_all(arg)),(arg).erase(unique(_all(arg)),end(arg))
#define getidx(ary,key) lower_bound(_all(ary),key)-begin(ary)
#define clr(a,b) memset((a),(b),sizeof(a))
#define bit(n) (1LL<<(n))
#define popcount(n) (__builtin_popcountll(n))

using namespace std;

template<class T>bool chmax(T &a, const T &b) { return (a<b)?(a=b,1):0;}
template<class T>bool chmin(T &a, const T &b) { return (b<a)?(a=b,1):0;}

using ll=long long;
using R=long double;
const R EPS=1e-9L; // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R& r){return(r > EPS)-(r < -EPS);}
inline R sq(R x){return sqrt(max(x,0.0L));}

const int dx[8]={1,0,-1,0,1,-1,-1,1};
const int dy[8]={0,1,0,-1,1,1,-1,-1};

const pid_t pid = getpid();
// Problem Specific Parameter:
const int limit = 100010;
int x[limit],y[limit];

using pii = pair<int,int>;
vector<pii> ary;

template<unsigned MOD>  class ModInt {
public:
	ModInt(): x(0) {}
	ModInt(signed y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}
	ModInt(signed long long y) : x(y >= 0 ? y % MOD : MOD - (-y) % MOD) {}


	// Arithmetic Oprators
	ModInt &operator+=(ModInt that) {
		if ((x += that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator-=(ModInt that) {
		if ((x += MOD - that.x) >= MOD) x -= MOD; 
		return *this;
	}
	ModInt &operator*=(ModInt that) {
		x = 1LL * x * that.x % MOD;
		return *this;
	}
	ModInt &operator/=(ModInt that) {
		return *this *= ModInt(get<1>(extgcd(that.x, int(MOD))));
	}
	ModInt &operator%=(ModInt that) {
		x %= that.x;
		return *this;
	}

	ModInt &operator+=(const int that) { return *this += ModInt(that);}
	ModInt &operator-=(const int that) { return *this -= ModInt(that);}
	ModInt &operator*=(const int that) { return *this *= ModInt(that);}
	ModInt &operator/=(const int that) { return *this /= ModInt(that);}
	ModInt &operator%=(const int that) { return *this %= ModInt(that);}

	// Comparators
	bool operator <(ModInt that) { return x < that.x; }
	bool operator >(ModInt that) { return x > that.x; }
	bool operator<=(ModInt that) { return x <= that.x; }
	bool operator>=(ModInt that) { return x >= that.x; }
	bool operator!=(ModInt that) { return x != that.x; }
	bool operator==(ModInt that) { return x == that.x; }

	// Utilities
	unsigned getval() const { return x;}
	ModInt operator+(ModInt that) const { return ModInt(*this) += that;}
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that;}
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that;}
	ModInt operator/(ModInt that) const { return ModInt(*this) /= that;}
	ModInt operator%(ModInt that) const { return ModInt(*this) %= that;}
	ModInt operator+(const int that) const { return ModInt(*this) += that;}
	ModInt operator-(const int that) const { return ModInt(*this) -= that;}
	ModInt operator*(const int that) const { return ModInt(*this) *= that;}
	ModInt operator/(const int that) const { return ModInt(*this) /= that;}
	ModInt operator%(const int that) const { return ModInt(*this) %= that;}
	ModInt operator=(const int that) { return *this = ModInt(that);}
	friend istream &operator>>(istream& is, ModInt &that) {ll tmp; is >> tmp; that = ModInt(tmp);return is;}
	friend ostream &operator<<(ostream& os, const ModInt &that) { return os << that.x; }
	
	ModInt power(ll n) const {
		ll b = 1LL, a = x;
		while(n){
			if(n & 1) b = b * a % MOD;
			a = a * a % MOD;
			n >>= 1;
		}
		return ModInt(b);
	}
private:
	unsigned x;
	
	inline auto extgcd(int a, int b) {
		if (b == 0) return make_tuple(a, 1, 0);
		tuple<int, int, int> ret = extgcd(b, a % b);
		swap(get<1>(ret), get<2>(ret));
		get<2>(ret) -= a / b * get<1>(ret);
		return ret;
	}
};

const int mod = 1000000007;
using mint = ModInt<mod>;
const mint ZERO = mint(0);
const mint ONE = mint(1);


template <int depth> struct Segment_tree {
	const static int h = depth;
	const static int n = 1 << h;

	using T = mint;
	T data[2 * n];
	const T out = ZERO;

	inline T vmerge(T l, T r) {return l + r;}

	void init() {
		fill_n(data, 2 * n, out);
	}

	void update(int p, T x) { // set value at position p
		for (data[p += n] += x; p > 1; p >>= 1){
			data[p >> 1] = vmerge(data[p], data[p ^ 1]);
		}
	}

	T query(int l, int r) {  // sum on interval [l, r)
		T resl = out, resr = out;
		for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
			if (l & 1) resl = vmerge(data[l++], resl);
			if (r & 1) resr = vmerge(resr, data[--r]);
		}
		return vmerge(resl, resr);
	}
};

Segment_tree<17> seg;

int main(void){
	int n,m;
	cin >> n >> m;

	rep(i,n) cin >> x[i];
	rep(i,m) cin >> y[i];


	int ci = -1;
	vector<int> vals = {0};
	
	rep(i,n){
		while(ci  < m and y[ci] < x[i]) ci++;

		int lft = -1;
		if(0 <= ci - 1 and ci - 1 < m) lft = x[i] - y[ci-1];
		int rht = -1;
		if(0 <= ci  and ci  < m) rht = y[ci] - x[i];

		
		if(lft != -1 and rht != -1){
			ary.push_back(pii(lft,-rht));
			vals.push_back(rht);
		}
	}

	sort(begin(vals),end(vals));
	vals.erase(unique(begin(vals),end(vals)),end(vals));
	const int k = vals.size();

	sort(begin(ary),end(ary));
	ary.erase(unique(begin(ary),end(ary)),end(ary));

	seg.init();
	seg.update(0,ONE);

	for(auto &elem:ary){
		const int pos = lower_bound(begin(vals),end(vals), -elem.second) - begin(vals);
		const mint cur = seg.query(0,pos);
		seg.update(pos,cur);
	}

	cout << seg.query(0,k).getval() << endl;

	return 0;
}

Measured memory_bytes: 3572