import sys
sys.setrecursionlimit(100000)
def num_steps(steps, cache={}):
    if steps in out or steps < 0 :
        return 0
    elif steps == 0:
        return 1

    if steps in cache:
        return cache[steps]
    else:
        one = num_steps(steps-1, cache)
        two = num_steps(steps-2, cache)
        ans = one + two
        cache[steps] = ans

        return ans%mod

n, m = map(int, input().split())
out = set(int(input()) for _ in range(m))
mod = 1000000007

print(num_steps(n))

