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[1] = 0
 
for i in range(2,n+1):
    if i in a :
      dp[i] += dp[i-1] +dp[i-2] 
dp[i] %= INF
 
print(dp[n])