n,m = map(int,input().split())
a = []
for _ in range(m):
    a.append(int(input()))

if n == 1:
    print(1)
elif n == 2:
    if 1 in a:
        print(1)
    else:
        print(2)
else:
    if 1 in a:
        b1 = 0
    else:
        b1 = 1
    if 2 in a:
        b2 = 0
    else:
        b2 = b1+1

    b3 = b1 + b2

    for i in range(3,n+1):
        if i in a:
            b3 = 0
        else:
            b3 = b1+b2
        if b3 > 1000000007:
            b3 = b3 % 1000000007
        b1 = b2
        b2 = b3
        if b1==b2==0:
            break

    print(b3)