import sys
input = sys.stdin.readline
n,m = map(int,input().split())
a = [0]*m
for i in range(m):
  a[i] = int(input())
dp = [0]*(n+1)
dp[0] = 1
if 1 in a:
  dp[1] = 0
else:
  dp[1] = 1

for j in range(2,n+1):
  if j in a:
    dp[j] = 0
  else:
    dp[j] = dp[j-1]+dp[j-2]
print(dp[n]%1000000007)