n,m = map(int,input().split())
a = set([int(input())for _ 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:
        continue
    dp[i] = (dp[i-1]+dp[i+2])%1000000007
print(dp[n])