N, M = map(int, input().split())
A = []
for _ in range(M):
    A.append(int(input()))

case = [0] * (N + 1)
case[0] = 1
if not 1 in A:
    case[1] = 1
for x in range(2, N + 1):
    if x in A:
        case[x] = 0
    elif x - 1 in A:
        case[x] = case[x - 2]
    else:
        case[x] = case[x - 1] + case[x - 2] % 1000000007

print(case[N]%1000000007)