import sys
input = sys.stdin.readline
n,m = map(int,input().split())
a = [int(input()) for _ in range(m)]
dp = [0]*(n+1)
dp[0] = 1
if 1 in a:
  dp[1] = 0
else:
  dp[1] = 1
for i in range(2,n+1):
  if i in a:
  else:
    dp[i] = dp[i-1]+dp[i-2]
print(dp[-1] % (10**9+7))