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

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

step = [0 for _ in range(N+1)]

ptr = 0

step[0] = 1
if ptr < M and A[ptr] != 1:
    step[1] = 1
else:
    ptr += 1

for i in range(2, N+1):
    if ptr < M and i == A[ptr]:
        ptr += 1
    else:
        step[i] = step[i-1] + step[i-2]


print(step[N] % (10**9+7))
