#define _USE_MATH_DEFINES
#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define MT make_tuple
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
#define RT return
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;
using vll = vector<ll>;

template<int MOD>
class ModInt {
public:
    ModInt() :value(0) {}
    ModInt(long long val) :value((int)(val<0 ? MOD + val % MOD : val % MOD)) { }

    ModInt& operator+=(ModInt that) {
        value = value + that.value;
        if (value >= MOD)value -= MOD;
        return *this;
    }
    ModInt& operator-=(ModInt that) {
        value -= that.value;
        if (value<0)value += MOD;
        return *this;
    }
    ModInt& operator*=(ModInt that) {
        value = (int)((long long)value * that.value % MOD);
        return *this;
    }
    ModInt &operator/=(ModInt that) {
        return *this *= that.inverse();
    }
    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 pow(long long k) const {
        ModInt n = *this, res = 1;
        while (k) {
            if (k & 1)res *= n;
            n *= n;
            k >>= 1;
        }
        return res;
    }
    ModInt inverse() const {
        long long a = value, b = MOD, u = 1, v = 0;
        while (b) {
            long long t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        return ModInt(u);
    }
    int toi() const { return value; }

private:
    int value;
};
typedef ModInt<1000000007> mint;
ostream& operator<<(ostream& os, const mint& x) {
    os << x.toi();
    return os;
}

template<class Val>
struct BinaryIndexedTree {
    int n;
    vector<Val> t;
    BinaryIndexedTree() {}
    BinaryIndexedTree(int _n) :n(_n + 1), t(_n + 1) {}
    void add(int k, Val val) {
        k++;
        while (k < n) {
            t[k] += val;
            k += (k&-k);
        }
    }
    void set(int k, Val val) {
        add(k, -sum(k, k + 1));
        add(k, val);
    }
    Val sum(int k) {
        Val r = 0;
        while (k > 0) {
            r += t[k];
            k -= (k&-k);
        }
        return r;
    }
    Val sum(int l, int r) {
        return sum(r) - sum(l);
    }
};

const int MAX = 100005;
int N, M, X[MAX], Y[MAX];

void solve() {
    cin >> N >> M;
    rep(i, N) cin >> X[i];
    rep(i, M) cin >> Y[i];

    vector<pii> A;
    vector<int> R{ 0 };

    rep(i, N) {
        if (X[i]<Y[0] || X[i]>Y[M - 1])continue;
        int j = lower_bound(Y, Y + M, X[i]) - Y;
        // (z, w1)->(z, w2), w1<w2の移動を避けるために
        // (z, w2), (z, w1)の順にみる
        A.emplace_back(X[i] - Y[j - 1], -(Y[j] - X[i]));
        R.push_back(Y[j] - X[i]);
    }
    sort(all(R));
    R.erase(unique(all(R)), R.end());
    sort(all(A));
    // ひとつの座標つき一度だけ加算
    A.erase(unique(all(A)), A.end());

    BinaryIndexedTree<mint> bit(sz(R));
    bit.add(0, 1);
    each(a, A) {
        int r = -a.second;
        int id_r = lower_bound(all(R), r) - R.begin();
        bit.add(id_r, bit.sum(id_r));
    }

    cout << bit.sum(sz(R)) << endl;
}

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}

Measured memory_bytes: 2548