#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<b;i++)
#define rrep(i,a,b) for(int i=a;i>=b;i--)
#define fore(i,a) for(auto &i:a)
#define all(x) (x).begin(),(x).end()
#pragma GCC optimize ("-O3")
using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); }
typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
//---------------------------------------------------------------------------------------------------
template<int MOD> struct ModInt {
    static const int Mod = MOD; unsigned x; ModInt() : x(0) { }
    ModInt(signed sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    ModInt(signed long long sig) { x = sig < 0 ? sig % MOD + MOD : sig % MOD; }
    int get() const { return (int)x; }
    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 = (unsigned long long)x * that.x % 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 inverse() const { long long a = x, b = MOD, u = 1, v = 0;
        while (b) { long long t = a / b; a -= t * b; std::swap(a, b); u -= t * v; std::swap(u, v); }
        return ModInt(u); }
    bool operator==(ModInt that) const { return x == that.x; }
    bool operator!=(ModInt that) const { return x != that.x; }
    ModInt operator-() const { ModInt t; t.x = x == 0 ? 0 : Mod - x; return t; }
};
template<int MOD> ostream& operator<<(ostream& st, const ModInt<MOD> a) { st << a.get(); return st; };
template<int MOD> ModInt<MOD> operator^(ModInt<MOD> a, unsigned long long k) {
    ModInt<MOD> r = 1; while (k) { if (k & 1) r *= a; a *= a; k >>= 1; } return r; }
typedef ModInt<1000000007> mint;
template<class V> struct BIT { BIT() {}  // [L, R)
    int NV;vector<V> bit;BIT(int n){init(n);}void init(int n){NV=1;while(NV<n)NV*=2;bit.resize(NV);}
    V operator[](int e) { V s = 0; e++; while (e) s += bit[e - 1], e -= e&-e; return s; }
    void add(int e, V v) { e++; while (e <= NV) bit[e - 1] += v, e += e&-e; }
    int lower_bound(V val) { V tv = 0; int i, ent = 0; for (i = NV - 1; i >= 0; i--)
        if(tv+bit[ent+(1<<i)-1]<=val)tv+=bit[ent+(1<<i)-1],ent += (1 << i);return ent;}
    V get(int L, int R) {assert(0 <= L); assert(R <= NV); assert(L <= R);
        V res = 0; if(R) res += operator[](R - 1); if (L) res -= operator[](L - 1);return res;}
    void clear() { bit.clear(); }};
/*---------------------------------------------------------------------------------------------------
　　　　　　　　　　　 ∧＿∧  
　　　　　 ∧＿∧ 　（´<_｀ ）　 Welcome to My Coding Space!
　　　　 （ ´_ゝ`）　/　 ⌒i     
　　　　／　　　＼　 　  |　|     
　　　 /　　 /￣￣￣￣/　　|  
　 ＿_(__ﾆつ/　    ＿/ .| .|＿＿＿＿  
　 　　　＼/＿＿＿＿/　（u　⊃  
---------------------------------------------------------------------------------------------------*/






int N, M, X[101010], Y[101010];
int A[101010], B[101010];
//---------------------------------------------------------------------------------------------------
void _main() {
    cin >> N >> M;
    rep(i, 0, N) cin >> X[i];
    rep(i, 0, M) cin >> Y[i];

    int n = 0;
    rep(i, 0, N) {
        if (X[i] < Y[0] or Y[M - 1] < X[i]) continue;

        A[n] = X[i] - *(lower_bound(Y, Y + M, X[i]) - 1);
        B[n] = *lower_bound(Y, Y + M, X[i]) - X[i];
        n++;
    }

    vector<int> z;
    z.push_back(0);
    rep(i, 0, n) z.push_back(A[i]), z.push_back(B[i]);
    sort(all(z));
    z.erase(unique(all(z)), z.end());
    rep(i, 0, n) {
        A[i] = lower_bound(all(z), A[i]) - z.begin();
        B[i] = lower_bound(all(z), B[i]) - z.begin();
    }

    BIT<mint> bit(z.size());
    vector<vector<int>> idx(z.size());
    rep(i, 0, n) idx[A[i]].push_back(B[i]);

    bit.add(0, 1);
    rep(x, 0, z.size()) {
        sort(all(idx[x]));
        idx[x].erase(unique(all(idx[x])), idx[x].end());
        sort(all(idx[x]), greater<int>());
        fore(y, idx[x]) bit.add(y, bit.get(0, y));
    }

    mint ans = bit.get(0, z.size());
    cout << ans << endl;
}

Measured memory_bytes: 10996