N,M = map(int,input().split())
a = [0]*M
for i in range(M):
    a[i] = int(input())

b = [(-1 if x in a else 0) for x in range(N+1)]

b[0] = 1

mod = 10**9+7
for i in range(1,N+1):
    if b[i] == -1:
        continue
    if i == 1:
        b[i] = b[0]
    else:
        b[i] = max(b[i-1],0) + max(b[i-2],0)
    b[i] %= mod

print(b[N])