div = 1000000007

n, m = map(int, input().split())
a = [int(input()) for i in range(m)]

f = [0] * (n + 1)
f[0] = 1

if 1 not in a:
    f[1] = 1

for i in range(2, n + 1):
    if i in a:
        continue
    f[i] = (f[i - 1] + f[i - 2]) % div

print(f[-1])
