n,m = map(int,input().split())
a = [int(input()) for i in range(m)]
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]) % 1000000007
#print(dp)
print(dp[n])