n, m = map(int, input().split())
list_score = []
for _ in range(m):
    list_score.append(int(input()))

dp = [0]*(n+1)
mod = pow(10, 9) + 7

dp[0] = 1
if list_score[0] == 1:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, n+1):
    if i in list_score:
        continue
    dp[i] = dp[i-1] + dp[i-2]

print(dp[n]%mod)