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

p = [0]*(n+1)
if n == 1 and m == 0:
    print(1)
elif n == 1 and m == 1:
    print(0)
else:
    p[0] = 1
    if 1 in bk:
        p[1] = 0
    else:
        p[1] = 1
    for i in range(n-1):
        if i+2 in bk:
            p[i+2] = 0
        else:
            p[i+2] = p[i]+p[i+1]
            if p[i+2] >= 1000000007:
                p[i+2] -= 1000000007

print(p[n])
