N, M = map(int,input().split())
a = [int(input()) for i in range(M)]
dp = [0 for i in range(N+1)]
dp[0] = 1
dp[1] = 1
for i in range(2,N+1)
  if (i-2 in a) and (i-1 in a):
    dp[-1] = 0
    break
  elif i-2 in a:
    dp[i] = dp[i-1]
  elif i-1 in a:
    dp[i] = dp[i-2]
  else:
    dp[i] = dp[i-1] + dp[i-2]

print(dp[-1]%(7+10**9))