N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
inf = 10**9+7

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

for i in range(2,N+1):
  if i in a:
    continue
  dp[i] = dp[i-1] + dp[i-2]
  dp[i] %= inf

print(dp[N]) 