#! /Library/Frameworks/Python.framework/Versions/3.7/bin/python3
D = 1000000007
n, m = map(int, input().split())
a = [0] * (10**5)
for i in range(m):
    a[int(input())] += 1

# 初期値
s = [0] * (n + 1)
s[0] = 1
if (a[1] == 1):
    s[1] = 0
else:
    s[1] = 1


def calc(n):
    if(a[n] == 1):
        return 0
    else:
        return (s[n - 1] + s[n - 2]) % D


def solver(n):
    for i in range(2, n + 1):
        s[i] = calc(i)


solver(n)
print(s[n])
