n,m = map(int,input().split())
dp = [0]*(n+1)
dp[1],dp[2] = 1,1

for _ in range(m):
  a = int(input())
  dp[a] = -1

for i in range(1,n-1):
  if dp[i+2]==-1:
    continue
  if dp[i]==-1 and dp[i+1]==-1:
    dp[i+2] = -1
  elif dp[i]==-1:
    dp[i+2] = dp[i+1]
  elif dp[i+1]==-1:
    dp[i+2] = dp[i]
  else:
    dp[i+2] = dp[i] + dp[i+1]
    
print(dp[n]%(10**9+7) if dp[n]!=-1 else 0)