n,m=map(int,input().split())
mod=10**9+7
a=[0]*(n+1)
dp=[0]*(n+1)
dp[0]=1
for i in range(m):
    a[int(input())]=1
    
if 1 in a:
    dp[1]=0
else:
    dp[1]=1
    
for j in range(2,n+1):
    if a[j]==0:
        dp[j]=dp[j-1]+dp[j-2] 
                  
print(dp[n]%mod)            

    
    

