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

n, m = map(int, input().split())
dp = [-1] * (n + 1)
for i in range(m):
    a = int(input())
    dp[a] = 0
    if i == 0 and a != 1:
        dp[1] = 1
mod = 10 ** 9 + 7

dp[0] = 1
for i in range(1, n):
    if dp[i + 1] == 0:
        continue
    dp[i + 1] = (dp[i] + dp[i - 1]) % mod
print(dp[n])