n, m = list(map(int, input().split()))
a = []
for i in range(m):
	a.append(int(input())
mod = 1000000007

memo = [0]*(n+1)
memo[0] = 1


for i in range(1, n+1):
    memo[i] = memo[i-1] + memo[i-2]
    if i in a:
        memo[i] = 0

print(memo[-1]%mod)