import sys
#from scipy.special import comb
#from scipy.misc import comb

from operator import mul
from functools import reduce

def cmb(n,r):
    r = min(n-r,r)
    if r == 0: return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1,r + 1))
    return over // under

sys.setrecursionlimit(100000)
nCr = {}
def cmb(n, r):
    if r == 0 or r == n: return 1
    if r == 1: return n
    if (n,r) in nCr: return nCr[(n,r)]
    nCr[(n,r)] = cmb(n-1,r) + cmb(n-1,r-1)
    return nCr[(n,r)]


def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

N,M = list(map(int, input().split()))

A = [0]*M

for i in range(M):
    A[i] = int(input())

A.append(N+1)

def step_comb(L):
    c = 0
    if L==1 or L == 0:
        c = 1
    else:
        for i in range(L//2 +1):
            j = L - 2*i
            #c += comb(j+i, i, exact=True)
            c += cmb(j+i, i)
    return c

total_comb = 1
NOW = 0
for a in A:
    if NOW == a:
        print(0)
        sys.exit()
    L = a-1-NOW
    total_comb *= step_comb(L)
    NOW = a + 1
    
print(total_comb % 1000000007 )
