from collections import deque

N, M = map(int, input().split())
A = [int(input()) for _ in range(M)]

tmp = [0 for _ in range(N + 1)]

if 1 not in A:
    tmp[1] = 1
    
if 2 not in A and N >= 2:
    tmp[2] = tmp[1] + 1

for i in range(3, N+1):
    
    if i not in A:
        tmp[i] = tmp[i-1] + tmp[i-2] 
        

    
print(tmp[-1]%(10**9+7))


