N,M = map(int,input().split())
a = [0]*M
for i in range(M):
    a[i] = int(input())

step = [0]*(N+1)
step[0] = 1
if 1 in a:
    step[1] = 0
else:
    step[1] = 1

for i in range(2,N+1):
    if i in a:
        step[i] = 0
    else:
        step[i] = (step[i-1] + step[i-2])%(10**9+7)

print(step[N])

#再起関数供養
def count_step(a,n):
    if n == 0:
        return 1
    if n == 1 and 1 not in a:
        return 1
    if n in a:
        return 0
    return (count_step(a,n-1)+count_step(a,n-2))%(10**9+7)