n,m=map(int,input().split())
a=list(int(input()) for _ in range(m))
if m==0:a=[0]
dp=[0]*(n+1)
dp[0]=1
if a[0]==1:
    dp[1]=0
else:
    dp[1]=1
safe=[]
for i in range(1,n+1):
    if i not in a:safe.append(i)
for i in safe:
    dp[i]=dp[i-1]+dp[i-2]
    dp[i] %= 1000000007
print(dp[n]%1000000007)