n,m = map(int, input().split())
a = [int(input()) for _ in range(m)]
dp = [0]*(n+1)
dp[0] = 1
dp[1] = (0 if 1 in a else 1)
for i in range(2,n+1):
    if i in a:continue
    dp[i] = (dp[i-1]+dp[i-2])%1000000007
print(dp[n])