N, M = map(int, input().split())
broken = [int(input()) for _ in range(M)]
div = 1000000007

comb_list = [0] * (N + 1)
comb_list[0] = 1
if 1 not in broken:
    comb_list[1] = 1

for i in range(2, N + 1):
    if i in broken:
        continue
    comb_list[i] = (comb_list[i - 1] + comb_list[i - 2]) % div

print(comb_list[-1])
