import sys
sys.setrecursionlimit(200000)
input = sys.stdin.readline

n, m = map(int, input().split())
a = [int(input()) for _ in range(m)]
dp = [0] * (n + 1)
mod = 10 ** 9 + 7

dp[0] = 1
if not 1 in a:
    dp[1] = 1
for i in range(1, n):
    if i + 1 in a:
        dp[i + 1] = 0
    else:
        dp[i + 1] = (dp[i] + dp[i - 1]) % mod
print(dp[n])