mod = 10**9+7
n, m = map(int, input().split())
stairs = [0]*(n+1)
broken = []
stairs[0] = 1

for i in range(m):
    b = int(input())
    if broken and b-1 == broken[-1]:
        print(0)
        exit(0)
    broken.append(b)

for i in range(n+1):
    if i in broken:
        continue
    if i >= 2:
        stairs[i] = stairs[i-1] + stairs[i-2]
    elif i == 1:
        stairs[i] = stairs[i-1]

print(stairs[-1]%mod)


