n,m=map(int,input().split())
a=[]
for i in range(m):
  a.append(int(input()))
dp=[1]
if 1 in a:
  dp.append(0)
else:
  dp.append(1)
for i in range(2,n+1):
  if i in a:
    dp.append(0)
  else:
    dp.append(dp[i-1]+dp[i-2])
print(dp[n]%1000000007)