N,M  = map(int, input().split())
A = {}
mod = 10**9+7
for i in range(M):
    a = int(input())
    A[a] = 1
    if a-1 in A:
        print(0, '_', i)
        exit()

stairs = [0 for _ in range(N+2)]
stairs[0] = 1

for i in range(N):
    if i+1 not in A:
        stairs[i+1] = (stairs[i] + stairs[i+1]) % mod
    if i+2 not in A:
        stairs[i+2] = (stairs[i] + stairs[i+2]) % mod
        
print(stairs[N])
