from itertools import accumulate
n,m=map(int,input().split())
dp=[0]*(n+1)
List=[int(input()) for i in range(m)]
List.sort()
step=0

dp[0]=1
dp[1]=1

if(List[0]==1):
    dp[1]=0
    step+=1
for i in range(2,n+1):
    # print(i,step)
    if(step<m and i==List[step]):
        step+=1
        dp[i]=0
    else:
        dp[i]=dp[i-2]+dp[i-1]
# print(List)
# print(dp)
print(dp[n]%((10**9)+7))