n, m = map(int, input().split())
broken = [int(input()) for _ in range(m)]

mod = 10 ** 9 + 7

dp = [0] * (n + 1)
dp[0] = 1
if 1 not in broken:
    dp[1] = 1

for i in range(2, n + 1):
    if i -1 not in broken:
        dp[i] = dp[i] + dp[i - 1]
    if i - 2 not in broken:
        dp[i] = dp[i] + dp[i - 2]
    
    dp[i] %= 1000000007
    
print(dp[n])