N, M = map(int, input().split())

a = []
for _ in range(M):
    a.append(int(input()))

val = [0,1]
for i in range(1, N + 1):
    ans = (val[0] + val[1]) % (10**9 +7)
    val[0] = val[1]
    val[1] = ans
    if i in a:
        val[1] = 0


print(ans)