n, m = list(map(int, input().split(' ')))

bads = {}
for i in range(m):
    bads[int(input())] = None

dp = [1, 1]
for i in range(2, n):
    dp.append(0)
    if i-1 not in bads:
        dp[i] += dp[i-1]
    if i-2 not in bads:
        dp[i] += dp[i-2]
    dp[i] %= 1000000007

print(dp[-1])
