N,M = map(int, input().split())
A = [int(input()) for i in range(M)]
dp = [0]*(N+1)
dp[0]=1
if 1 in A:
    dp[1]= 0
else:
    dp[1]=1
for i in range(2,N+1):
    if i in A:
        dp[i] == 0
    else:
        dp[i] = (dp[i-1]+dp[i-2])%(10**9+7)
print(dp[-1])