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

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

val = [0,1]
j = 0
for i in range(1, N + 1):
    ans = val[0] + val[1]
    val[0] = val[1]
    val[1] = ans
    if i == a[j]:
        val[1] = 0
        if len(a) - 1 != j:
            j += 1

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