n, m = map(int, input().split())
a = list(int(input()) for _ in range(m))

MOD = 1000000007
dp = [0] * (n + 1)

dp[0] = 1
if 1 not in a:
    dp[1] = 1
for i in range(2, n + 1):
    if i in a:
        continue
    dp[i] = (dp[i - 1] + dp[i - 2]) % MOD
            
print(dp[n])
