#! /Library/Frameworks/Python.framework/Versions/3.7/bin/python3
D = 1000000007
n, m = map(int, input().split())
a = [0] * (10**6)
for i in range(m):
    a[int(input())] += 1

# 初期値
s0 = 1
if (a[1] == 1):
    s1 = 0
else:
    s1 = 1


def calc(l, acc1, acc2):
    # print("calc(l, acc1, acc2):" + str(l) + str(acc1) + str(acc2))
    if (l == 1):
        return acc2
    else:
        oldacc2 = acc2
        if (a[n - l + 2] == 1):
            acc2 = 0
        else:
            acc2 = (acc1 + acc2) % D
        acc1 = oldacc2
        return calc(l - 1, acc1, acc2)


print(calc(n, s0, s1))
