import sys
imput=sys.stdin.readline
n,m=map(int,input().split())
l=[int(input()) for i in range(m)]
#print(l)
dp=[0]*(n+1)
dp[0]=1
if 1 not in l:
    dp[1]=1
else:dp[1]=0 
for i in range(2,n+1):
    if i in l:
        dp[i]=0
    else:
        dp[i]=(dp[i-1]%(10**9+7)+dp[i-2]%(10**9+7))%(10**9+7)
print(dp[-1]%(10**9+7))