N,M = map(int,input().split())
mod = 1000000007

dp = [0]*(N+1)
dp[0] = 1
A = []

for _ in range(M):
    k = int(input())
    A.append(k)

if 1 in A:
   dp[1] = 0
   if 2 in A:
       dp[2] = 0
else:
    dp[1] = 1
    
for i in range(2,N+1):
    if i not in A:
        dp[i] = (dp[i-1] + dp[i-2])%mod

print(dp[-1])