n,m,*a=map(int,open(0).read().split())
b=[-1]*(n+1)
if m!=0:
    for i in a:
        b[i]=0
    if a[0]==1 and a[1]==2:
        continue
    elif a[0]==1:
        b[2]=1
    elif a[0]==2:
        b[1]=1
    else:    
        b[1],b[2]=1,2
else:    
        b[1],b[2]=1,2        
for i in range(3,n+1):
    if b[i]==-1:
        b[i]=(b[i-1]+b[i-2])%1000000007
print(b[-1])