mod = 10**9 + 7

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

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

print(dp[n])