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

b = [0]*N

if 1 not in a:
    b[0] = 1

if 2 not in a:
    if b[0] == 1:
        b[1] = 2
    else:
        b[1] = 1

for i in range(2,N):
    if i+1 not in a:
        if b[i-2] != 0:
            b[i]+= b[i-2]
        if b[i-1] != 0:
            b[i]+= b[i-1]

print(b[N-1]%1000000007)