n,m = map(int,input().split())
a = [int(input()) for _ in range(m)]
mod = 1000000007

dp = [0]*(n+1)
dp[0] = 1
if 1 in a:
    dp[1] = 0
    dp[2] = 1
else:
    dp[1] = 1
    
for i in range(1,n+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2] 

ans = dp[n] % mod
print(ans)