n,m = map(int,input().split())
A = list()
for i in range(m):
    a = int(input())
    A.append(a)
dp = [0]*(n+1)
dp[0] = 1
if 1 not in A:
    dp[1] = 1
for i in range(2,n+1):
    if i not in A:
        dp[i] = dp[i-2] + dp[i-1]
        dp[i] = dp[i]%1000000007
print(dp[-1]%1000000007)