n,m = map(int,input().split())
if m!=0:
    ls = [int(input()) for _ in range(m)]

else:
    ls = []

dp = [0 for _ in range(n+1)]
dp[0]=1

if 1 in ls:
    dp[1]= 0
else:
    dp[1]= 1

for i in range(2,n+1):
    if i in ls :
        dp[i] = 0
    else:
        dp[i] = dp[i-1]+dp[i-2]
        
print(dp[n]%(10**9+7))