n,m = map(int, input().split())
a = [int(input()) for i in range(m)]
mod = 10**9+7
# i番目にたどり着く総数
dp = [0 for i in range(n+1)]
dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1
for i in range(n-1):
    if i+2 in a:
        dp[i+2] = 0
    else:
        dp[i+2] = (dp[i] + dp[i+1])%mod
print(dp[n])