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]
    val[0] = val[1]
    val[1] = ans
    if i in a:
        val[1] = 0

print(ans%(10**9+7))