import sys
import collections
ns = lambda: sys.stdin.readline().rstrip()
ni = lambda: int(ns())
nm = lambda: map(int, sys.stdin.readline().split())
nl = lambda: list(nm())
nsm = lambda: map(str, sys.stdin.readline().split())
nsl = lambda: list(nsm())

mod = 1000000007

n, m = nm()
dp = [0] * (n + 2)
for i in range(m):
    tmp = ni()
    dp[tmp] = -1
dp[0] = 1
for i in range(n):
    if i + 1 <= n:
        if dp[i + 1] != -1 and dp[i] != -1:
            dp[i + 1] += dp[i] % mod
            dp[i + 1] %= mod
    if i + 2 <= n:
        if dp[i + 2] != -1 and dp[i] != -1:
            dp[i + 2] += dp[i] % mod
            dp[i + 2] %= mod
if dp[n] = -1:
    print(0)
else:
    print(dp[n] % mod)
