#include <bits/stdc++.h>

using namespace std;

template <typename T>
T power(T a, long long b) {
  T r = 1;
  while (b) {
    if (b & 1) {
      r *= a;
    }
    a *= a;
    b >>= 1;
  }
  return r;
}

template <typename T>
T inverse(T a, T m) {
  a %= m;
  if (a < 0) {
    a += m;
  }
  T b = m, u = 0, v = 1;
  while (a) {
    T t = b / a;
    b -= a * t;
    swap(a, b);
    u -= v * t;
    swap(u, v);
  }
  if (u < 0) {
    u += m;
  }
  return u;
}

template <int _P>
struct modnum {
  static constexpr int P = _P;

 private:
  int v;

 public:
  modnum() : v(0) {
  }

  modnum(long long _v) {
    v = _v % P;
    if (v < 0) {
      v += P;
    }
  }

  explicit operator int() const {
    return v;
  }

  bool operator==(const modnum& o) const {
    return v == o.v;
  }

  bool operator!=(const modnum& o) const {
    return v != o.v;
  }

  modnum inverse() const {
    return modnum(::inverse(v, P));
  }

  modnum operator-() const {
    return modnum(v ? P - v : 0);
  }
  
  modnum operator+() const {
    return *this;
  }

  modnum& operator++() {
    v++;
    if (v == P) {
      v = 0;
    }
    return *this;
  }
  
  modnum& operator--() {
    if (v == 0) {
      v = P;
    }
    v--;
    return *this;
  }

  modnum operator++(int) {
    modnum r = *this;
    ++*this;
    return r;
  }
  
  modnum operator--(int) {
    modnum r = *this;
    --*this;
    return r;
  }

  modnum& operator+=(const modnum& o) {
    v += o.v;
    if (v >= P) {
      v -= P;
    }
    return *this;
  }

  modnum operator+(const modnum& o) const {
    return modnum(*this) += o;
  }

  modnum& operator-=(const modnum& o) {
    v -= o.v;
    if (v < 0) {
      v += P;
    }
    return *this;
  }

  modnum operator-(const modnum& o) const {
    return modnum(*this) -= o;
  }

  modnum& operator*=(const modnum& o) {
    v = (int) ((long long) v * o.v % P);
    return *this;
  }

  modnum operator*(const modnum& o) const {
    return modnum(*this) *= o;
  }
  
  modnum& operator/=(const modnum& o) {
    return *this *= o.inverse();
  }

  modnum operator/(const modnum& o) const {
    return modnum(*this) /= o;
  }
};

template <int _P>
ostream& operator<<(ostream& out, const modnum<_P>& n) {
  return out << int(n);
}

template <int _P>
istream& operator>>(istream& in, modnum<_P>& n) {
  long long _v;
  in >> _v;
  n = modnum<_P>(_v);
  return in;
}

using num = modnum<1000000007>;

template <typename T>
class fenwick {
 public:
  vector<T> fenw;
  int n;

  fenwick(int n) : n(n) {
    fenw.resize(n);
  }

  void modify(int x, T v) {
    while (x < n) {
      fenw[x] += v;
      x |= x + 1;
    }
  }

  T query(int x) {
    T res{};
    while (x >= 0) {
      res += fenw[x];
      x = (x & (x + 1)) - 1;
    }
    return res;
  }
};

int main() {
#ifdef LOCAL
  freopen("input.txt", "r", stdin);
#endif
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> x(n);
  for (int i = 0; i < n; ++i) {
    cin >> x[i];
  }
  vector<int> y(m);
  for (int i = 0; i < m; ++i) {
    cin >> y[i];
  }
  vector<pair<int, int>> p;
  vector<int> d;
  for (int i = 0, j = 0; i < n; ++i) {
    while (j < m && y[j] < x[i]) {
      ++j;
    }
    if (j == m) {
      break;
    }
    if (j) {
      p.emplace_back(x[i] - y[j - 1], y[j] - x[i]);
      d.push_back(y[j] - x[i]);
    }
  }
  sort(d.begin(), d.end());
  d.erase(unique(d.begin(), d.end()), d.end());
  m = d.size();
  sort(p.begin(), p.end());
  p.erase(unique(p.begin(), p.end()), p.end());
  n = p.size();
  for (int i = 0; i < n; ++i) {
    p[i].second = lower_bound(d.begin(), d.end(), p[i].second) - d.begin();
  }
  fenwick<num> fenw(m + 1);
  fenw.modify(0, 1);
  vector<num> dp(n);
  for (int i = 0, j = 0; i < n; ) {
    while (j < n && p[j].first == p[i].first) {
      dp[j] = fenw.query(p[j].second);
      ++j;
    }
    while (i < j) {
      fenw.modify(p[i].second + 1, dp[i]);
      ++i;
    }
  }
  cout << fenw.query(m) << "\n";
  return 0;
}


Measured memory_bytes: 2804