n,m = map(int,input().split())
a_list = []
for i in range(m):
    a_list.append(int(input()))
    
mod = 1000000007

dp = [0]*n
dp[0] = 1
dp[1] = 1
if 1 in a_list:
    dp[0] = 0
if 2 in a_list:
    dp[1] = 0
for i in range(2,n):
    if (i+1) in a_list:
        continue
    else:
        dp[i] = dp[i-1] + dp[i-2]
        dp[i] %= mod
print(dp[-1])