n,m = list(map(int, input().split()))
s = [0 for i in range(n+1)]
t = [-1 for i in range(n+1)]
for i in range(m):
    x = int(input())
    s[x] = 1

def dx(r):
    global t
    if t[r]>=0:
        return t[r]
    x=0
    y=0
    #print(i)
    if r==n-2:
        return 2
    if r==n-1:
        return 1
    if r==n:
        return 0
    if s[r+1] == 0:
        x=dx(r+1)
    if s[r+2] == 0:
        y=dx(r+2)
    #print([i,x,y])
    t[r]=(x+y)%1000000007
    return (x+y)%1000000007

ans=dx(0)

print(ans)