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[-2] + val[-1]
    val.append(ans)
    if len(a) > 0:
        if i == a[0]:
            val[-1] = 0
            a.pop(0)

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