import sys

n, m = map(int, input().split())
A = []
for i in range(m):
    A.append(int(input()))
dp = [0] * (n+1)
mod = 1000000007
dp[0] = 1
if 1 in A:
    if 2 in A:
        print(0)
        sys.exit()
else:
    dp[1] = 1
for i in range(2, n+1):
    if i in A:
        dp[i] = 0
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % mod
print(dp[-1])