N,M = map(int,input().split())
A = []
for i in range(M):
    A.append(int(input()))
count = [0] * (N+1)
count[0] = 1
mod = 10 ** 9 + 7
if 1 in A:
    if 2 in A:
        print(0)
        exit()
    count[2] = 1
    start = 3
else:
    count[1] = 1
    start = 2
for i in range(start, N+1):
    if i in A:
        continue
    count[i] = count[i-1] + count[i-2]
    count[i] %= mod

print(count[N])