import sys
input = sys.stdin.readline

n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
MOD = 10 ** 9 + 7

dp = [0] * (n + 1)
dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(2, n + 1):
    if i not in a:
        dp[i] = (dp[i - 1] + dp[i - 2]) % MOD

print(dp[-1])