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

A = []

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

step = [0] * (N + 1)

step[0] = 1

for s in range(1, N + 1):
    if A[s]:
        step[s] = 0
        continue
    if s == 1:
        step[s] = 1
        continue
    else:
        step[s] = step[s - 1] + step[s - 2]
        step[s] %= 1000000007

print(step[N])
