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

counter_arr = [0]*(N+1)

counter_arr[0] = 1
next_broken = -1
if len(broken_lst) != 0:
    next_broken = broken_lst.pop(0)
last_broken = -1

for i in range(0, N-1):
    flug = 0
    if i+1 == next_broken:
        flug = 1
#        print("p0", i, counter_arr)
    elif i+1 == last_broken:
        pass
#        print("p1",i, counter_arr)
    else:
        counter_arr[i+1] += counter_arr[i]
        counter_arr[i+1] %= 10**9 + 7
#        print("p2",i,  counter_arr)

    if i + 2 == next_broken:
        flug = 1
#        print("p3",i, counter_arr)
    else:
        counter_arr[i+2] += counter_arr[i]
        counter_arr[i+2] %= 10**9 + 7
#        print("p4",i, counter_arr)
    
    if flug == 1:
        last_broken = next_broken
        if len(broken_lst) != 0:
            next_broken = broken_lst.pop(0)

if last_broken != N - 1:
    counter_arr[-1] += counter_arr[-2]
counter_arr[-1] %= 10**9 + 7

print(counter_arr[-1])