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 len(a) > 0:
        if i == a[0]:
            val[1] = 0
            a.pop(0)

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