import sys



sys.setrecursionlimit(10000000)

import os

import math

import bisect

import collections

import itertools

import heapq

import re

import queue



# import fractions



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)

# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)



MOD = 10 ** 9 + 7

MAX = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    N, M = il()

    A = set(iln(M))

    dp = [0]*(N+1)

    dp[0] = 1



    for n in range(1, N+1):

        if n in A:

            dp[n] = 0

        else:

            dp[n] = dp[n-1] + dp[n-2]

    print((dp[N]%MOD))





if __name__ == '__main__':

    main()

import sys



sys.setrecursionlimit(10000000)

import os

import math

import bisect

import collections

import itertools

import heapq

import re

import queue



# import fractions



ii = lambda: int(sys.stdin.buffer.readline().rstrip())

il = lambda: list(map(int, sys.stdin.buffer.readline().split()))

fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))

iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]



iss = lambda: sys.stdin.buffer.readline().decode().rstrip()

sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))

isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]



lcm = lambda x, y: (x * y) // math.gcd(x, y)

# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)



MOD = 10 ** 9 + 7

MAX = float('inf')





def main():

    if os.getenv("LOCAL"):

        sys.stdin = open("input.txt", "r")



    N, M = il()

    A = set(iln(M))

    dp = [0]*(N+1)

    dp[0] = 1



    for n in range(1, N+1):

        if n in A:

            dp[n] = 0

        else:

            dp[n] = (dp[n-1] + dp[n-2])%MOD

    print((dp[N]%MOD))





if __name__ == '__main__':

    main()

import sys

sys.setrecursionlimit(10000000)
import os
import math
import bisect
import collections
import itertools
import heapq
import re
import queue

# import fractions
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)
MOD = 10**9 + 7
MAX = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    N, M = il()
    A = set(iln(M))
    dp = [0] * (N + 1)
    dp[0] = 1
    for n in range(1, N + 1):
        if n in A:
            dp[n] = 0
        else:
            dp[n] = dp[n - 1] + dp[n - 2]
    print((dp[N] % MOD))


if __name__ == "__main__":
    main()

import sys

sys.setrecursionlimit(10000000)
import os
import math
import bisect
import collections
import itertools
import heapq
import re
import queue

# import fractions
ii = lambda: int(sys.stdin.buffer.readline().rstrip())
il = lambda: list(map(int, sys.stdin.buffer.readline().split()))
fl = lambda: list(map(float, sys.stdin.buffer.readline().split()))
iln = lambda n: [int(sys.stdin.buffer.readline().rstrip()) for _ in range(n)]
iss = lambda: sys.stdin.buffer.readline().decode().rstrip()
sl = lambda: list(map(str, sys.stdin.buffer.readline().decode().split()))
isn = lambda n: [sys.stdin.buffer.readline().decode().rstrip() for _ in range(n)]
lcm = lambda x, y: (x * y) // math.gcd(x, y)
# lcm = lambda x, y: (x * y) // fractions.gcd(x, y)
MOD = 10**9 + 7
MAX = float("inf")


def main():
    if os.getenv("LOCAL"):
        sys.stdin = open("input.txt", "r")
    N, M = il()
    A = set(iln(M))
    dp = [0] * (N + 1)
    dp[0] = 1
    for n in range(1, N + 1):
        if n in A:
            dp[n] = 0
        else:
            dp[n] = (dp[n - 1] + dp[n - 2]) % MOD
    print((dp[N] % MOD))


if __name__ == "__main__":
    main()

-            dp[n] = dp[n - 1] + dp[n - 2] +            dp[n] = (dp[n - 1] + dp[n - 2]) % MOD