N,M = map(int,input().split())
a = [int(input()) for i in range(M)]
m = 10**9+7

dp = [0]*(N+1)
dp[0] = 1
if 1 not in a:
	dp[1] = 1
for i in range(2,N+1):
    if i not in a:
    	dp[i] = dp[i-1] + dp[i-2]
    	dp[i] %= m
print(dp[-1])