n,m = map(int, input().split())
list = [0] * n
list[0] = 1
if n >= 2:
    list[1] = 2
if n >= 3:
    for i in range(2, n):
        list[i] = list[i - 2] + list[i - 1]



ans = 1
o = 0
for i in range(m):
    a = int(input())
    if a == o:
        ans = 0
        break
    if a > o + 1:
        ans = (ans * list[a - o - 2]) % 1000000007
    o = a + 1

if a + 1 < n:
    ans = (ans * list[n - a - 2]) % 1000000007
print(ans)