n,m = map(int ,input().split())
a = list(set([int(input()) for _ in range(m)]))

mod = 10**9+7
ans = [0]*(n+1)
ans [0] = 1
if 1 not in a: ans[1] = 1

for i in range(2,n+1):
  if i in a: continue
  ans[i] = ans[i-1] + ans[i-2]
print(ans[-1]%mod)