
import sys
imput =sys.stdin.readline

p = 10**9 + 7

N,M =map(int,input().split())
lis = [0]*N

for _ in range(M):
    i = int(input())-1
    lis[i] = -1


if lis[0]!=-1:
    lis[0] =1
if lis[1]!=-1:
    lis[1] =1 + max(0,lis[0])

for i in range(N-2):
    i += 2
    if lis[i]!=-1:
        lis[i]= (max(0,lis[i-1])+max(0,lis[i-2]))%p

print(lis[-1])