#include <bits/stdc++.h>
#define int long long
#define ll long long
using ull = unsigned long long;
using namespace std;
#define dump(x)                             \
    if (dbg) {                              \
        cerr << #x << " = " << (x) << endl; \
    }
#define overload4(_1, _2, _3, _4, name, ...) name
#define FOR1(n) for (ll i = 0; i < (n); ++i)
#define FOR2(i, n) for (ll i = 0; i < (n); ++i)
#define FOR3(i, a, b) for (ll i = (a); i < (b); ++i)
#define FOR4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FORR(i, a, b) for (int i = (a); i <= (b); ++i)
#define bit(n, k) ((n >> k) & 1) /*nのk bit目*/
namespace mydef {
const int INF = 1ll << 60;
const int MOD = 1e9 + 7;
template <class T>
bool chmin(T& a, const T& b) {
    if (a > b) {
        a = b;
        return 1;
    } else
        return 0;
}
template <class T>
bool chmax(T& a, const T& b) {
    if (a < b) {
        a = b;
        return 1;
    } else
        return 0;
}
void Yes(bool flag = true) {
    if (flag)
        cout << "Yes" << endl;
    else
        cout << "No" << endl;
}
void No(bool flag = true) {
    Yes(!flag);
}
void YES(bool flag = true) {
    if (flag)
        cout << "YES" << endl;
    else
        cout << "NO" << endl;
}
void NO(bool flag = true) {
    YES(!flag);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T& val) {
    std::fill((T*)array, (T*)(array + N), val);
}
bool dbg = false;
}  // namespace mydef
using namespace mydef;
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(), (v).end()
#define SZ(x) ((int)(x).size())
#define vi vector<int>
#define vvi vector<vector<int>>
#define vp vector<pair<int, int>>
#define vvp vector<vector<pair<int, int>>>
#define pi pair<int, int>
//#define P pair<int, int>
//#define V vector<int>
//#define S set<int>
#define asn ans

template <uint MD>
struct ModInt {
    using M = ModInt;
    const static M G;
    uint v;
    ModInt(ll _v = 0) { set_v(_v % MD + MD); }
    M& set_v(uint _v) {
        v = (_v < MD) ? _v : _v - MD;
        return *this;
    }
    explicit operator bool() const { return v != 0; }
    M operator-() const { return M() - *this; }
    M operator+(const M& r) const { return M().set_v(v + r.v); }
    M operator-(const M& r) const { return M().set_v(v + MD - r.v); }
    M operator*(const M& r) const { return M().set_v(ull(v) * r.v % MD); }
    M operator/(const M& r) const { return *this * r.inv(); }
    M& operator+=(const M& r) { return *this = *this + r; }
    M& operator-=(const M& r) { return *this = *this - r; }
    M& operator*=(const M& r) { return *this = *this * r; }
    M& operator/=(const M& r) { return *this = *this / r; }
    bool operator==(const M& r) const { return v == r.v; }
    M pow(ll n) const {
        M x = *this, r = 1;
        while (n) {
            if (n & 1)
                r *= x;
            x *= x;
            n >>= 1;
        }
        return r;
    }
    M inv() const { return pow(MD - 2); }
    /*
    M inv() const {
        long long b = MD, u = 1, v = 0;
        long long a = (*this).v;
        while (b) {
            long long t = a / b;
            a -= t * b;
            swap(a, b);
            u -= t * v;
            swap(u, v);
        }
        u %= MD;
        if (u < 0)
            u += MD;
        return M{u};
    }
    */
    friend ostream& operator<<(ostream& os, const M& r) { return os << r.v; }
    friend istream& operator>>(istream& is, M& r) { return is >> r.v; }
};
using Mint = ModInt<MOD>;
const int MN = 1000000;
Mint fact[MN], iFac[MN];

void first() {
    fact[0] = Mint(1);
    for (int i = 1; i < MN; i++)
        fact[i] = fact[i - 1] * Mint(i);
    iFac[MN - 1] = fact[MN - 1].inv();
    for (int i = MN - 1; i >= 1; i--) {
        iFac[i - 1] = iFac[i] * Mint(i);
    }
    assert(fact[2345] * iFac[2345] == Mint(1));
}
Mint C(int n, int k) {
    if (n < k || k < 0)
        return Mint(0);
    return fact[n] * iFac[k] * iFac[n - k];
}

Mint total(int N) {
    if (N <= 0)
        return Mint{0};
    else
        return Mint{3} * N * Mint{2}.pow(N - 1) - Mint{2}.pow(N + 1) + 2;
}
template <class T>
struct Matrix {
    vector<vector<T>> A;

    Matrix() {}

    Matrix(size_t n, size_t m) : A(n, vector<T>(m, 0)) {}

    Matrix(size_t n) : A(n, vector<T>(n, 0)){};

    size_t height() const {
        return (A.size());
    }

    size_t width() const {
        return (A[0].size());
    }

    inline const vector<T>& operator[](int k) const {
        return (A.at(k));
    }

    inline vector<T>& operator[](int k) {
        return (A.at(k));
    }

    static Matrix I(size_t n) {
        Matrix mat(n);
        for (int i = 0; i < n; i++)
            mat[i][i] = 1;
        return (mat);
    }

    Matrix& operator+=(const Matrix& B) {
        size_t n = height(), m = width();
        assert(n == B.height() && m == B.width());
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                (*this)[i][j] += B[i][j];
        return (*this);
    }

    Matrix& operator-=(const Matrix& B) {
        size_t n = height(), m = width();
        assert(n == B.height() && m == B.width());
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                (*this)[i][j] -= B[i][j];
        return (*this);
    }

    Matrix& operator*=(const Matrix& B) {
        size_t n = height(), m = B.width(), p = width();
        assert(p == B.height());
        vector<vector<T>> C(n, vector<T>(m, 0));
        for (int i = 0; i < n; i++)
            for (int j = 0; j < m; j++)
                for (int k = 0; k < p; k++)
                    C[i][j] = (C[i][j] + (*this)[i][k] * B[k][j]);
        A.swap(C);
        return (*this);
    }

    Matrix& operator^=(long long k) {
        Matrix B = Matrix::I(height());
        while (k > 0) {
            if (k & 1)
                B *= *this;
            *this *= *this;
            k >>= 1LL;
        }
        A.swap(B.A);
        return (*this);
    }

    Matrix operator+(const Matrix& B) const {
        return (Matrix(*this) += B);
    }

    Matrix operator-(const Matrix& B) const {
        return (Matrix(*this) -= B);
    }

    Matrix operator*(const Matrix& B) const {
        return (Matrix(*this) *= B);
    }

    Matrix operator^(const long long k) const {
        return (Matrix(*this) ^= k);
    }

    friend ostream& operator<<(ostream& os, Matrix& p) {
        size_t n = p.height(), m = p.width();
        for (int i = 0; i < n; i++) {
            os << "[";
            for (int j = 0; j < m; j++) {
                os << p[i][j] << (j + 1 == m ? "]\n" : ",");
            }
        }
        return (os);
    }


    T determinant() {
        Matrix B(*this);
        assert(width() == height());
        T ret = 1;
        for (int i = 0; i < width(); i++) {
            int idx = -1;
            for (int j = i; j < width(); j++) {
                if (B[j][i] != 0)
                    idx = j;
            }
            if (idx == -1)
                return (0);
            if (i != idx) {
                ret *= -1;
                swap(B[i], B[idx]);
            }
            ret *= B[i][i];
            T vv = B[i][i];
            for (int j = 0; j < width(); j++) {
                B[i][j] /= vv;
            }
            for (int j = i + 1; j < width(); j++) {
                T a = B[j][i];
                for (int k = 0; k < width(); k++) {
                    B[j][k] -= B[i][k] * a;
                }
            }
        }
        return (ret);
    }
};


/*
int memo[20] = {}; 
int f(int N) {
    if (memo[N])
        return memo[N];
    int ret = 0;
    for (int i = 1; i <= N; i++) {
        ret += f(N - i) * i * i;
    }
    return memo[N] = ret;
} 
int memo2[100];
int g(int N) {
    if (memo[N])
        return memo[N];
    return memo[N] = 4 * g(N - 1) - 2 * g(N - 2) + g(N - 3);
}
*/

int N, M;
vi X;

Mint f(int n) {
    Matrix<Mint> M(3), v(3, 1);
    M[0][0] = 4;
    M[0][1] = -2;
    M[0][2] = 1;
    M[1][0] = 1;
    M[2][1] = 1;
    v[0][0] = 5;
    v[1][0] = 1;
    v[2][0] = 0;
    return ((M ^ (n)) * v)[2][0];
}

void solve() {
    Matrix<Mint> M(3), v(3, 1), w(1, 3), A(3, 3);
    M[0][0] = 4;
    M[0][1] = -2;
    M[0][2] = 1;
    M[1][0] = 1;
    M[2][1] = 1;
    v[0][0] = 5;
    v[1][0] = 1;
    v[2][0] = 0;
    w[0][2] = 1;
    A[0][2] = 5;
    A[1][2] = 1;
    auto I = Matrix<Mint>::I(3);

    auto Mat = I;
    for (int i = 1; i < X.size(); i++) {
        int d = X[i] - X[i - 1];
        if (i != 1)
            Mat *= (I - A);
        Mat *= M ^ d;
    }


    cout << (w * Mat * v)[0][0] << endl;
}

signed main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    cin >> N >> M;
    X.emplace_back(0);
    for (int i = 0; i < M; i++) {
        int x;
        cin >> x;
        X.emplace_back(x);
    }
    X.emplace_back(N);

    solve();
    return 0;
}


Measured memory_bytes: 12124