#include<stdio.h>
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<string.h>

#ifdef LOCAL
#define eprintf(...) fprintf(stderr, __VA_ARGS__)
#else
#define NDEBUG
#define eprintf(...) do {} while (0)
#endif
#include<cassert>

using namespace std;

typedef long long LL;
typedef vector<int> VI;

#define REP(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define EACH(i,c) for(__typeof((c).begin()) i=(c).begin(),i##_end=(c).end();i!=i##_end;++i)

template<class T> inline void amin(T &x, const T &y) { if (y<x) x=y; }
template<class T> inline void amax(T &x, const T &y) { if (x<y) x=y; }
template<class Iter> void rprintf(const char *fmt, Iter begin, Iter end) {
    for (bool sp=0; begin!=end; ++begin) { if (sp) putchar(' '); else sp = true; printf(fmt, *begin); }
    putchar('\n');
}
template<unsigned MOD> struct ModInt {
    static const unsigned static_MOD = MOD;
    unsigned x;
    void undef() { x = (unsigned)-1; }
    bool isnan() const { return x == (unsigned)-1; }
    inline int geti() const { return (int)x; }
    ModInt() { x = 0; }
    ModInt(const ModInt &y) { x = y.x; }
    ModInt(int y) { if (y<0 || (int)MOD<=y) y %= (int)MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt(long long y) { if (y<0 || MOD<=y) y %= MOD; if (y<0) y += MOD; x=y; }
    ModInt(unsigned long long y) { if (MOD<=y) x = y % MOD; else x = y; }
    ModInt &operator+=(const ModInt y) { if ((x += y.x) >= MOD) x -= MOD; return *this; }
    ModInt &operator-=(const ModInt y) { if ((x -= y.x) & (1u<<31)) x += MOD; return *this; }
    ModInt &operator*=(const ModInt y) { x = (unsigned long long)x * y.x % MOD; return *this; }
    ModInt &operator/=(const ModInt y) { x = (unsigned long long)x * y.inv().x % MOD; return *this; }
    ModInt operator-() const { return (x ? MOD-x: 0); }

    ModInt inv() const {
	unsigned a = MOD, b = x; int u = 0, v = 1;
	while (b) {
	    int t = a / b;
	    a -= t * b; swap(a, b);
	    u -= t * v; swap(u, v);
	}
	if (u < 0) u += MOD;
	return ModInt(u);
    }
    ModInt pow(long long y) const {
	ModInt b = *this, r = 1;
	if (y < 0) { b = b.inv(); y = -y; }
	for (; y; y>>=1) {
	    if (y&1) r *= b;
	    b *= b;
	}
	return r;
    }
    friend ModInt operator+(ModInt x, const ModInt y) { return x += y; }
    friend ModInt operator-(ModInt x, const ModInt y) { return x -= y; }
    friend ModInt operator*(ModInt x, const ModInt y) { return x *= y; }
    friend ModInt operator/(ModInt x, const ModInt y) { return x *= y.inv(); }
    friend bool operator<(const ModInt x, const ModInt y) { return x.x < y.x; }
    friend bool operator==(const ModInt x, const ModInt y) { return x.x == y.x; }
    friend bool operator!=(const ModInt x, const ModInt y) { return x.x != y.x; }
};

const LL MOD = 1000000007;
//const LL MOD = 998244353;
typedef ModInt<MOD> Mint;

template<class T> struct Fenwick {
    int n;
    T* d;
    Fenwick() : n(0), d(NULL) {}
    Fenwick(int n_) : n(n_) {
	d = new T[n_]();
    }
    Fenwick(const Fenwick &y) : n(y.n) {
	d = new T[n];
	memcpy(d, y.d, sizeof (T) * n);
    }
    ~Fenwick() {
	delete[] d; d = NULL;
	n = 0;
    }
    friend void swap(Fenwick &x, Fenwick &y) {
	swap(x.n, y.n); swap(x.d, y.d);
    }
    Fenwick& operator=(Fenwick y) {
	swap(*this, y);
	return *this;
    }
    inline void add(int i, const T &x) {
	for (; i<n; i|=i+1) d[i] += x;
    }
    inline T sum(int r) {
	T s = T();
	for (; r; r&=r-1) s += d[r-1];
	return s;
    }
    T sum(int l, int r) {
	return sum(r) - sum(l);
    }
};

template<class T> vector<int> compress(const vector<T> &v, vector<T> *unq=NULL) {
    int n = v.size();
    vector<pair<T, int> > t(n);
    for (int i=0; i<n; i++) t[i] = make_pair(v[i], i);
    sort(t.begin(), t.end());
    vector<int> r(n);
    int cur = 0;
    for (int i=0, k=0; i<n; i++) {
	if (t[k].first < t[i].first) k = i, cur++;
	r[t[i].second] = cur;
    }
    if (unq) {
	unq->resize(cur+1);
	cur = 0;
	for (int i=0; i<n; i++)
	    if (i == 0 || t[i-1].first < t[i].first)
		(*unq)[cur++] = t[i].first;
    }
    return r;
}

int N, M;
int X[100011], Y[100011];

void MAIN() {
    scanf("%d%d", &N, &M);
    REP (i, N) scanf("%d", X+i);
    REP (i, M) scanf("%d", Y+i);

    vector<pair<int, int> > P;
    REP (i, N) {
	int k = lower_bound(Y, Y+M, X[i]) - Y;
	if (k == M || k == 0) continue;
	P.emplace_back(X[i] - Y[k-1], Y[k] - X[i]);
    }

    N = -1;
    sort(P.begin(), P.end());
    P.erase(unique(P.begin(), P.end()), P.end());
    VI val(P.size()+1);
    REP (i, P.size()) val[i] = P[i].second;
    VI c = compress(val);

    Fenwick<Mint> F(val.size());
    F.add(0, 1);

    for (int i=0; i<(int)P.size(); ) {
	int j = i;
	while (j < (int)P.size() && P[i].first == P[j].first) j++;
	for (int k=j-1; k>=i; k--) {
	    int pos = c[k];
	    Mint t = F.sum(pos);
	    F.add(pos, t);
	}
	i = j;
    }

    Mint ans = F.sum(val.size());
    printf("%d\n", ans.geti());
}

int main() {
    int TC = 1;
//    scanf("%d", &TC);
    REP (tc, TC) MAIN();
    return 0;
}



Measured memory_bytes: 3316