N,M = map(int,input().split())
bro = [int(input()) for i in range(M)]
mod = 10**9 + 7
dp = [0]*(N+1)
dp[0] = 1
if bro[0] != 1:
    dp[1] = 1
else:
    del bro[0]
for i in range(2,N+1):
    if len(bro) == 0:
        dp[i]= (dp[i-1] + dp[i-2]) % mod
    elif bro[0] == i:
        del bro[0]
        continue
    else:
        dp[i]= (dp[i-1] + dp[i-2]) % mod
print(dp[-1] % mod)
