N,M = map(int,input().split())
A = [int(input()) for _ in range(M)]

dp = [0]*(N+1)
dp[0] = 1
dp[1] = 1

for i in range(2,N+1):
  if i not in A:
    dp[i] = (dp[i-1] + dp[i-2])%1000000007
  else:
    dp[i] = 0

print(dp[N])