N, M = map(int, input().split())

mod_num = 10 ** 9 + 7
a = [0] * M

for i in range(M):
    a[i] = int(input())

val = [0,1]
j = 0
for i in range(1, N + 1):
    ans = (val[0] + val[1]) % mod_num
    val[0] = val[1]
    val[1] = ans
    if i in a:
        val[1] = 0

 
print(ans)