n,m = map(int, input().split( ))
a = [] 
mod = 10**9+7
for _ in range(m):
    a.append(int(input()))

dp = [0]*(n+1)
dp[0] = 1
if a[0]!=1:
    dp[1] = 1

A = set(a)
 
for i in range(2,n+1):
    if i not in A:
        dp[i] = (dp[i-1]+dp[i-2])%mod
print(dp[n])


