n,m=map(int,input().split())
a=[]
for i in range(m):
  a.append(int(input()))

dp = [0]*(n+1)
dp[0] = 1
if 1 not in a:
  dp[1] = 1

for i in range(2,n+1):
  if i in a:
    continue

  dp[i] += dp[i-1] + dp[i-2]
  dp[i] = dp[i] % 1000000007
print(dp[n])