def dp(n):
    d=[0]*(n+1)
    if n==1:
        return 1
    else:
         d[0]=1
         if a[1]==0:
            d[1]=1
         else:
            d[1]=0
         for i in range(2,n+1):
            if a[i]==0:
                d[i]=d[i-1]+d[i-2]%1000000007
            else:
                d[i]=0
         return d[n]

n,m=map(int, input().split())
a=[0]*(n+1)
for i in range(0,m):
    k=int(input())
    a[k]=1
print(dp(n))