// includes {{{
#include<iostream>
#include<iomanip>
#include<algorithm>
#include<vector>
#include<stack>
#include<queue>
#include<map>
#include<set>
#include<tuple>
#include<cmath>
#include<random>
#include<cassert>
// #include<deque>
// #include<multiset>
// #include<bitset>
// #include<cstring>
// #include<bits/stdc++.h>
// }}}
using namespace std;
using ll = long long;

int n, m;
const int mod = 1e9 + 7;

/// --- ModInt Library {{{ ///
#include <ostream>
template < ll mod = (ll) 1e9 + 7 >
struct ModInt {
  // math {{{
  static inline ll extgcd(ll a, ll b, ll &x, ll &y) {
    ll d;
    return b == 0 ? (x = 1, y = 0, a) : (d = extgcd(b, a % b, y, x), y -= a / b * x, d);
  }
  static inline ll modinv(ll a) {
    ll x = 0, y = 0;
    extgcd(a, mod, x, y);
    if(x < 0) x += mod;
    return x;
  }
  static inline ll modpow(ll a, ll b) {
    if(b < 0) b = -b, a = modinv(a);
    ll r = 1;
    a %= mod;
    while(b) {
      if(b & 1) r = r * a % mod;
      a = a * a % mod;
      b >>= 1;
    }
    return r;
  }
  // }}}

  ll val;
  constexpr ModInt() : val(0) {}
  constexpr ModInt(ll t) {
    val = t % mod;
    if(val < 0) val += mod;
  }

private:
  // strict constructor
  constexpr ModInt(ll t, int) : val(t) {}

public:
  template < class T >
    explicit operator T() {
      return T(val);
    }
  // ModInt <arithmetic-operator>[=] ModInt {{{
  ModInt operator+(ModInt const &rhs) const {
    ModInt tmp = *this;
    tmp += rhs;
    return tmp;
  }
  ModInt operator-(ModInt const &rhs) const {
    ModInt tmp = *this;
    tmp -= rhs;
    return tmp;
  }
  ModInt operator*(ModInt const &rhs) const {
    ModInt tmp = *this;
    tmp *= rhs;
    return tmp;
  }
  ModInt operator/(ModInt const &rhs) const {
    ModInt tmp = *this;
    tmp /= rhs;
    return tmp;
  }
  ModInt &operator+=(ModInt const &rhs) {
    val = val + rhs.val;
    if(val >= mod) val -= mod;
    return *this;
  }
  ModInt &operator-=(ModInt const &rhs) { return *this += -rhs; }
  ModInt &operator*=(ModInt const &rhs) {
    val = val * rhs.val % mod;
    return *this;
  }
  ModInt &operator/=(ModInt const &rhs) { return *this *= rhs.inv(); }
  // }}}
  // increment, decrement {{{
  ModInt operator++(int) {
    ModInt tmp = *this;
    val = val + 1;
    if(val >= mod) val = 0;
    return tmp;
  }
  ModInt operator--(int) {
    ModInt tmp = *this;
    val = val == 0 ? mod - 1 : val - 1;
    return tmp;
  }
  ModInt &operator++() {
    val = val + 1;
    if(val >= mod) val = 0;
    return *this;
  }
  ModInt &operator--() {
    val = val == 0 ? mod - 1 : val - 1;
    return *this;
  }
  // }}}
  ModInt operator-() const { return ModInt(val == 0 ? 0 : mod - val, 0); }
  // ModInt <arithmetic-operator>[=] T {{{
  template < typename T >
    ModInt operator+(T const &rhs) const {
      return ModInt(val + rhs % mod);
    }
  template < typename T >
    ModInt operator-(T const &rhs) const {
      return ModInt(mod + val - rhs % mod);
    }
  template < typename T >
    ModInt operator*(T const &rhs) const {
      return ModInt(val * (rhs % mod));
    }
  template < typename T >
    ModInt operator/(T const &rhs) const {
      return ModInt(val * modinv(rhs));
    }
  template < typename T >
    ModInt &operator+=(T const &rhs) {
      val = (mod + val + rhs % mod) % mod;
      return *this;
    }
  template < typename T >
    ModInt &operator-=(T const &rhs) {
      val = (mod + val - rhs % mod) % mod;
      return *this;
    }
  template < typename T >
    ModInt &operator*=(T const &rhs) {
      val = val * (mod + rhs % mod) % mod;
      return *this;
    }
  template < typename T >
    ModInt &operator/=(T const &rhs) {
      val = val * modinv(rhs, mod) % mod;
      return *this;
    }
  // }}}
  ModInt inv() const { return ModInt(modinv(val), 0); }
  ModInt operator~() const { return inv(); }
  friend ostream &operator<<(ostream &os, ModInt const &mv) {
    os << mv.val;
    return os;
  }
  // T <arithmetic-operator> ModInt {{{
  friend constexpr ModInt operator+(ll a, ModInt const &mv) {
    return ModInt(a % mod + mv.val);
  }
  friend constexpr ModInt operator-(ll a, ModInt const &mv) {
    return ModInt(a % mod - mv.val);
  }
  friend constexpr ModInt operator*(ll a, ModInt const &mv) {
    return ModInt((mod + a % mod) * mv.val % mod, 0);
  }
  friend constexpr ModInt operator/(ll a, ModInt const &mv) {
    return ModInt((mod + a % mod) * modinv(mv.val) % mod, 0);
  }
  // }}}
  // power {{{
  ModInt operator^(ll x) const { return pow(*this, x); }
  ModInt &operator^=(ll x) {
    val = modpow(val, x);
    return *this;
  }
  friend ModInt pow(ModInt x, ll y) { return ModInt(modpow(x.val, y), 0); }
  // }}}
};
/// }}}--- ///

using mint = ModInt<>;

/// --- Matrix mult pow Library {{{ ///

template < class T >
vector< vector< T > > mult(vector< vector< T > > a, vector< vector< T > > b) {
  assert(a[0].size() == b.size());
  vector< vector< T > > res(a.size(), vector< T >(b[0].size(), 0));
  for(size_t i = 0; i < a.size(); i++) {
    for(size_t j = 0; j < b[0].size(); j++) {
      for(size_t k = 0; k < b.size(); k++) {
        res[i][j] += a[i][k] * b[k][j];
      }
    }
  }
  return res;
}

template < class T >
vector< vector< T > > makeE(int n) {
  vector< vector< T > > r(n, vector< T >(n, 0));
  for(int i = 0; i < n; i++) r[i][i] = T(1);
  return r;
}

template < class T >
vector< vector< T > > pow(vector< vector< T > > a, ll k) {
  assert(a.size() == a[0].size());
  vector< vector< T > > r = makeE< T >(a.size());
  while(k) {
    if(k & 1) r = mult(r, a);
    a = mult(a, a);
    k >>= 1;
  }
  return r;
}

/// }}}--- ///

using Vec = vector< mint >;
using Mat = vector< Vec >;

int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  cin >> n >> m;
  
  Mat v{
    {1},
    {1},
    {1},
  };
  
  Mat t{ // 1が禁止だったときの[2]の値
    {4},
    {2},
    {1},
  };

  Mat A{
    {2, 2, 1},
    {1, 1, 1},
    {1, 0, 1},
  };

  Mat C{ // これが前回はdp[x] = 0だった, と扱う場合のA
    {1, 2, 1},
    {0, 1, 1},
    {0, 0, 1},
  };

  int last = 1;
  for(int i = 0; i < m; i++) {
    int x;
    cin >> x;
    if(x == 1) {
      v = t;
    } else {
      auto B = pow(A, x - last);
      v = mult(mult(C, B), v);
    }
    last = x + 1;
  }

  auto B = pow(A, n - last);
  v = mult(B, v);
  cout << v[0][0] << endl;
  return 0;
}


Measured memory_bytes: 384