n, m = list(map(int, input().split()))
broken = []
for i in range(m):
    broken.append(int(input()))
MOD = 10 ** 9 + 7
dp = [0] * (n+1)
dp[0] = 1
if 1 not in broken:
    dp[1] = 1
for i in range(2, n+1):
    if i not in broken:
        dp[i] = (dp[i-1] + dp[i-2])%MOD

print(dp[-1])