import numpy as np
from math import factorial as fac

N,M=  map(int, input().split())
broken_steps=[]

for m in range(M):
    broken_steps.append(int(input()))

for i in range(len(broken_steps)-1):
    if broken_steps[i+1]-broken_steps[i]==1:
        print("{}".format(0))
        FLG=True

if FLG!=True:        
    count=0
    for two_step in range(M,N//2+1):
        one_step=N-two_step*2
        count+=fac(two_step+one_step)/(fac(two_step)*fac(one_step))

    print("{}".format(count%1000000007))