import sys

read = sys.stdin.read

n, m, *a = map(int, read().split())
mod = 1000000007
dp = [0] * (n+1)
dp[0] = 1
if a[0] == 1:
    dp[1] = 0
    a.pop(0)
else:
    dp[1] = 1
for i in range(2, n+1):
    if a and i == a[0]:
        a.pop(0)
        dp[i] == 0
    else:
        dp[i] = (dp[i-1] + dp[i-2]) % mod
print(dp[-1])
