n, m = [int(x) for x in input().split()]

a = [int(input()) for x in range(m)]
_MOD = 1000000007

dp = [0] * (n + 1)
dp[0] = 1

if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1

for i in range(1,n):
    if (i + 1) in a:
        dp[i + 1] = 0
    else:
        dp[i + 1] = (dp[i] + dp[i - 1]) % _MOD

print(dp[n])