n,m = map(int,input().split())
a = [0] * m
for i in range(m):
    a[i] = int(input())
 
MOD = 10 ** 9 + 7
dp = [0] * (n + 1)
dp[0] = 1
 
for i in range(1, n + 1):
    if i in a:
        continue
    x = dp[i - 1]
    if i > 1:
        x += dp[i - 2]
    dp[i] = x % MOD
ans = dp[n]
print(ans)