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

s[0] = 1
s[1] = 1 if n-1 not in a else 0

for i in range(2, n+1):
    if i in a:
        continue
    s[i] = (s[i-1] + s[i-2]) % 1000000007


print(s[n])