from collections import deque
n, m = map(int, input().split())
a = set(int(input()) for _ in range(m))
M = 1_000_000_007
dp = {}
dp[0] = 1
for i in range(1, n+1):
    if i in a:
        dp[i] = 0
        continue
    if i - 2 < 0:
        dp[i] = dp[i-1]
    else:
        dp[i] = dp[i-1] + dp[i-2]

print(dp[n] % M)