#!/usr/bin/env pypy3

import sys
sys.dont_write_bytecode = True
stdin = sys.stdin
input = stdin.readline
#sys.setrecursionlimit(100000)

#import numpy as np
#import scipy as sp

# Python 3 modules: https://docs.python.org/3/library/

import math, itertools, operator
from math import *
from math import factorial as fact
from operator import itemgetter, attrgetter
from itertools import permutations, combinations
from functools import reduce, lru_cache
# Use scipy for stats: https://docs.scipy.org/doc/scipy/reference/stats.html
# Before Python 3.5.  Import from math after it.
from fractions import gcd
from fractions import Fraction as Frac

inf = float('inf')

def lcm(a, b):
    return a * b // gcd(a,b)

def perm(a, b):
    import scipy.special
    return scipy.special.perm(a, b, exact = True)

def comb(a, b):
    import scipy.special
    return scipy.special.comb(a, b, exact = True)

def dfact(n):
    import scipy.special
    return scipy.special.factorial2(n, exact = True)

def prod(l):
    return reduce(operator.mul, l)

def input_ints(func = input, sep = None, conv = int):
    return list(map(conv, func().split(sep = sep)))

################################################################################

N, M = list(map(int, input().split()))
A = [None for i in range(M)]
for i in range(M):
    A[i] = int(input())
#A = list(map(int, stdin.read().split()))

BROKEN = [False for i in range(N)]
for a in A:
    BROKEN[a] = True

@lru_cache(maxsize = None)
def dp(cur):
    if cur > N:
        return 0
    if cur == N:
        return 1
    if BROKEN[cur]:
        return 0
    return dp(cur + 1) + dp(cur + 2)

print(dp(0) % 1000000007)


### FIXED CODE ###

#!/usr/bin/env pypy3

import sys
sys.dont_write_bytecode = True
stdin = sys.stdin
input = stdin.readline
sys.setrecursionlimit(10000000)

#import numpy as np
#import scipy as sp

# Python 3 modules: https://docs.python.org/3/library/

import math, itertools, operator
from math import *
from math import factorial as fact
from operator import itemgetter, attrgetter
from itertools import permutations, combinations
from functools import reduce, lru_cache
# Use scipy for stats: https://docs.scipy.org/doc/scipy/reference/stats.html
# Before Python 3.5.  Import from math after it.
from fractions import gcd
from fractions import Fraction as Frac

inf = float('inf')

def lcm(a, b):
    return a * b // gcd(a,b)

def perm(a, b):
    import scipy.special
    return scipy.special.perm(a, b, exact = True)

def comb(a, b):
    import scipy.special
    return scipy.special.comb(a, b, exact = True)

def dfact(n):
    import scipy.special
    return scipy.special.factorial2(n, exact = True)

def prod(l):
    return reduce(operator.mul, l)

def input_ints(func = input, sep = None, conv = int):
    return list(map(conv, func().split(sep = sep)))

################################################################################

N, M = list(map(int, input().split()))
A = [None for i in range(M)]
for i in range(M):
    A[i] = int(input())
#A = list(map(int, stdin.read().split()))

BROKEN = [False for i in range(N)]
for a in A:
    BROKEN[a] = True

@lru_cache(maxsize = None)
def dp(cur):
    if cur > N:
        return 0
    if cur == N:
        return 1
    if BROKEN[cur]:
        return 0
    return dp(cur + 1) + dp(cur + 2)

print(dp(0) % 1000000007)