N,M = map(int, input().split())
A = []
for a in range(M):
	A.append(int(input()))
	
DP = [0] * (N + 1)	
DP[0] = 1

mod = (10 ** 9) + 7

for i in range(1,N+1):
	if i in A:
		DP[i] = 0
	else:
		DP[i] = DP[i-1] + DP[i-2]

print(DP[N] % (mod))