from collections import defaultdict, deque, Counter
from heapq import heappush, heappop, heapify
from itertools import permutations, accumulate, combinations, combinations_with_replacement
from math import sqrt, ceil, floor, factorial
from bisect import bisect_left, bisect_right
from copy import deepcopy
from operator import itemgetter
from functools import reduce
from fractions import gcd
import sys
def I(): return int(input())
def Is(): return map(int, input().split())
def LI(): return list(map(int, input().split()))
def TI(): return tuple(map(int, input().split()))
def IR(n): return [I() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def TIR(n): return [TI() for _ in range(n)]
def S(): return input()
def Ss(): return input().split()
def LS(): return list(input())
def SR(n): return [S() for _ in range(n)]
def SsR(n): return [Ss() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
sys.setrecursionlimit(10**6)
MOD = 10**9+7
INF = float('inf')


n, m = Is()
A = IR(m)
dp = [0]*(n+3)
dp[0] = 1

A.sort(reverse=True)
tmp = A.pop()
if tmp == 1:
    dp[1] = 0
    if len(A) > 0:
        tmp = A.pop()
else:
    dp[1] = 1

for i in range(n+1):
    if tmp == i+2:
        dp[i+2] = 0
        if len(A) > 0:
            tmp = A.pop()
    else:
        dp[i+2] += dp[i+1] + dp[i]

print(dp[n] % MOD)
