n,m = map(int,input().split())
a = set([int(input()) for _ in range(m)])
dp = [0]*(n+1)
INF = 1000000007

dp[0] = 1
if 1 not in a:
  dp[1] = 1
  
else:
  dp[0]= [0]

for i in range(2,n+1):
    if i not in a :
      dp[i] += dp[i-1] #n-1 段目が安全なら
      dp[i] += dp[i-2] #n-2 段目が安全なら
dp[i] %= INF

print(dp[n])