# -*- coding: utf-8 -*-
def stairs_count(now, goal, memo):
    if memo[now] is not None:
        return memo[now]

    step1 = 0
    step2 = 0

    # step1
    if now + 1 == goal:
        step1 = 1
    else:
        step1 = stairs_count(now+1, goal, memo)

    # step2
    if now + 2 > goal:
        step2 = 0
    elif now + 2 == goal:
        step2 = 1
    else:
        step2 = stairs_count(now+2, goal, memo)

    memo[now] = (step1 + step2) % 1000000007
    return memo[now]


n, m  = map(int, input().split())
memo = [None for i in range(n)]
for _ in range(m):
    a = int(input())
    memo[a] = 0

root = stairs_count(0, n, memo)
print(root)
