n,k=map(int,input().split())
d=[0]*n
s=[0]*n

if k !=0:
    for i in range(k):
        p=int(input())
        d[p-1]=1

 
if d[0]==1:
    s[0]=0
else:
    s[0]=1
 
if d[1]==1:
    s[1]=0
else:
    s[1]= s[0]+1
 
 
for i in range(2,n):
    if d[i]==1:
        s[i]=0
    else:
        s[i]=(s[i-1]+s[i-2])%1000000007
 
print( s[n-1] % 1000000007)
