n,m=map(int,input().split())
a=[]

for i in range(m):
  b=int(input())
  a.append(b)
    
def count(x):
    if x==-1:
        return 0
    elif x==0:
        return 1
    elif x in a:
        return 0
    else:
        return (count(x-2)+count(x-1))%1000000007
    
print(count(n))
