n, m = list(map(int, input().split()))
a = []
for i in range(m):
    a.append(int(input()))
dp = [0 for _ in range(n+1)]
dp[0] = 1
if 1 in a:
    dp[1] = 0
else:
    dp[1] = 1
for i in range(2, n+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i - 2] + dp[i - 1]
print(dp[n] % 1000000007)
