import numpy as np
n,m = map(int,input().split())
a = [int(input()) for i in range(m)]

dp = [0] * (n+1)
for i in range(n+1):
     if i in a:
          dp[i] = 0
     elif i == 0 or i == 1:
          dp[i] = 1
     else:
          dp[i] = (dp[i-1] + dp[i-2])%1000000007
print(dp[n])