import sys

mod = int(1e9+7)

def dfs(i,dp,bad):
    if i == 0:
      return 1
    if i in dp:
      return dp[i]
    dp[i] = 0
    for d in (1,2):
      x = i-d;
      if 0 <= x and x not in bad:
        dp[i] += dfs(x)
        dp[i] %= mod
    return dp[i]

n,m = (int(a) for a in input().split())
bad = set()
for _ in range(m):
  a = int(input())
  bas.add(a)
print(dfs(n,dict(),bad))
