n, m = map(int,input().split())
a = [int(input()) for i in range(m)]
p = [0 for i in range(n+1)]
for i in range(1,n+1):
    if i in a:
        p[i] = 0
    elif i == 1:
        p[i] = 1
    elif i == 2:
        p[i] = p[1] + 1
    else:
        p[i] = p[i-1] + p[i-2]
print(p[n] % (10**9 + 7))